Intra-Industry Trade Dynamics: Analyzing China's
产业内贸易动态：中国的产业内贸易分析

Oil Crop Sector
油料作物部门

Abstract

This paper provides a comprehensive analysis of intra-industry trade in the global economy, focusing on China's oil crop industry. It traces the evolution of international trade theories from classical to contemporary perspectives, shedding light on the underlying reasons and profound impacts of goods and services exchange among nations.
本文以中国油料作物产业为研究对象，对全球经济中的产业内贸易进行了全面的分析。它追溯了国际贸易理论从古典到当代的演变，揭示了国家之间商品和服务交换的根本原因和深刻影响。

For the inherent complexity of intra-industry trade, this paper defines it, discusses its types and characteristics, and analyzes the reasons and effects. It highlights the significance of intra-industry trade as a key element in the current global trade paradigm, offering strategic insights crucial for economic development and the evolution of trade patterns in developing economies. Through a blend of theoretical analysis and empirical evidence, the research uncovers the subtle dynamics of intra-industry trade, supported by comprehensive analyses and in-depth case studies of China's oil crop industry.
针对产业内贸易固有的复杂性，本文对其进行了界定，探讨了产业内贸易的类型和特征，并分析了其产生的原因和影响。它强调了产业内贸易作为当前全球贸易模式中一个关键要素的重要性，提供了对发展中经济体的经济发展和贸易模式演变至关重要的战略见解。本研究采用理论分析与实证研究相结合的方法，通过对中国油料作物产业的全面分析和深入的案例研究，揭示了产业内贸易的微妙动态。

The paper concludes that intra-industry trade serves as a critical catalyst for industrial advancement and economic transformation. It demonstrates that variations in consumer preferences and product differentiation significantly influence intra-industry trade, particularly benefiting commodities such as sunflower seeds, sesame, and flaxseeds. Additionally, the study highlights the dual role of market size disparities in trade, underscoring the significant impact of market forces on trade dynamics.
产业内贸易是产业进步和经济转型的重要催化剂。它表明，消费者偏好和产品差异化的变化显着影响产业内贸易，特别是有利于商品，如向日葵籽，芝麻和亚麻籽。此外，研究报告还强调了市场规模差异在贸易中的双重作用，强调了市场力量对贸易动态的重大影响。

In essence, this paper presents a strategic roadmap for nations like China to leverage their intra-industry trade potential. It advocates for the adoption of innovation, diversification, and strategic policy initiatives to enhance global competitiveness and drive sustainable economic growth, thereby outlining a path for the effective utilization of intra-industry trade in the global economic landscape.
从本质上讲，本文为中国等国家提供了一个战略路线图，以利用其产业内贸易潜力。它倡导采取创新、多样化和战略政策举措，以提高全球竞争力，推动可持续经济增长，从而为在全球经济格局中有效利用产业内贸易勾勒出一条道路。

Key words: intra-industry trade; oil crop industry; consumer preferences; product differences; GL index
关键词：产业内贸易;油料作物产业;消费者偏好;产品差异; GL指数

1.Introduction

In the tide of globalization, international trade has become a key force to promote the development of the world economy. Intra-industry trade, as an important branch of international trade, is becoming increasingly important in the context of global economic integration. It not only reflects the deepening of economic ties between countries, but also an important embodiment of the development of modern international trade theory. Compared with traditional inter-industry trade, intra-industry trade emphasizes the mutual trading of different products within the same industry, and this form of trade is often closely related to product differentiation, technological progress and diversity of consumer preferences.
在全球化的浪潮中，国际贸易已成为推动世界经济发展的关键力量。产业内贸易作为国际贸易的一个重要分支，在全球经济一体化的背景下显得越来越重要。它不仅反映了国家间经济联系的深化，也是现代国际贸易理论发展的重要体现。与传统的产业间贸易相比，产业内贸易强调同一产业内不同产品的相互交易，这种贸易形式往往与产品差异化、技术进步和消费者偏好的多样性密切相关。

The earliest references to inter-industry trade were made by Hilgerdt and Ohlin.¹Although this was recognized early on, these early references to this phenomenon fell silent for many years due to postwar trade theorists' concerns about improvements to the Heckscher-Ohlin-Samuelson (H-O-S) model, and the lack of any documented evidence of intra-industry trade.
最早提到产业间贸易的是希尔格特和奥林。 ¹ 虽然这一点很早就被认识到，但由于战后贸易理论家对Heckscher-Ohlin-Samuelson（H-O-S）模型的改进感到担忧，以及缺乏任何关于产业内贸易的文献证据，这些早期对这一现象的提及多年来一直保持沉默。

In the following discussion, this paper will analyze the definition, types, causes of intra-industry trade and its impact on modern international trade.By combining theoretical analysis and case study of China's characteristic oil crop industry, this paper aims to provide a more comprehensive understanding of intra-industry trade and provide a reference for the strategic positioning of developing countries such as China in global trade.
在接下来的论述中，本文将分析产业内贸易的定义、类型、成因及其对现代国际贸易的影响，通过理论分析与中国特色油料作物产业的案例研究相结合，旨在对产业内贸易有一个更全面的认识，为中国等发展中国家在全球贸易中的战略定位提供参考。

2.Theoretical Background
2.理论背景

After World War II, with the rise of international trade, the theory of intra-industry trade slowly attracted the attention of economists. Since then, the theory of intra-industry trade has slowly been established.²
第二次世界大战后，随着国际贸易的兴起，产业内贸易理论慢慢引起了经济学家的注意。此后，产业内贸易理论慢慢建立起来。 ²

As an important part of global economy, international trade theory has experienced the evolution from classical to modern, revealing the deep reasons and extensive influence of goods and services exchange between countries. Mercantilism, as one of the earliest views on trade, emphasized the accumulation of gold and silver through trade surpluses to enhance national wealth and power. This view prevailed in the seventeenth and eighteenth centuries and prompted governments to adopt export incentives and import restrictions. Mercantilism, however, was limited in that it ignored the reciprocal nature of trade and failed to foresee the widespread benefits that free trade would bring.
作为全球经济的重要组成部分，国际贸易理论经历了从古典到现代的演变，揭示了国与国之间商品和服务交换的深层原因和广泛影响。重商主义作为最早的贸易观之一，强调通过贸易顺差积累黄金和银，以增强国家财富和实力。这种观点在17世纪和18世纪盛行，促使各国政府采取出口激励和进口限制措施。然而，重商主义是有限的，因为它忽视了贸易的互惠性质，也没有预见到自由贸易将带来的广泛利益。

With the development of economics, the theory of absolute advantage came into being. Adam Smith proposed that if a country is more efficient in producing a certain commodity than other countries, that is, it has absolute advantage, then it should specialize in producing this commodity and exchange other commodities with other countries through trade. This theory not only emphasizes the difference of production efficiency, but also highlights the mutual benefit of trade.
随着经济学的发展，绝对优势理论应运而生。亚当·斯密提出，如果一个国家生产某种商品的效率比其他国家高，即具有绝对优势，那么它就应该专门生产这种商品，并通过贸易与其他国家交换其他商品。这一理论既强调生产效率的差异性，又强调贸易的互利性。

What further deepens the understanding of trade is David Ricardo's theory of comparative advantage. The theory states that even if a country does not have an absolute advantage in the production of all commodities, it can still achieve trade gains by focusing on the production of commodities that are relatively less disadvantaged. The theory of comparative advantage reveals the universality of international trade, i.e., that different countries can improve overall welfare through specialized production and trade.
进一步深化对贸易理解的是大卫李嘉图的比较优势理论。该理论认为，即使一个国家在所有商品的生产中不具有绝对优势，它仍然可以通过专注于相对不那么不利的商品的生产来实现贸易收益。比较优势理论揭示了国际贸易的普遍性，即，不同的国家可以通过专业化生产和贸易来改善整体福利。

Hechscher and Ohlin further developed trade theory and proposed the Hechscher-Ohlin model based on factor endowment differences. The model assumes that countries tend to export goods that use more of their relatively abundant elements and import goods that use more of their relatively scarce elements. The H-O model also predicts the impact of trade on factor prices, namely the factor price equalization theorem, which points out that international trade will make countries obtain equal relative and absolute income of homogeneous factors. ³However, in the examination of reality, it was found that the H-O theory was inconsistent with the situation, resulting in the Leontief puzzle. The process of exploring the causes of Leontief's enigma itself became the turning point and driving force for the development of international trade theory after the war.⁴
Hechscher和Ohlin进一步发展了贸易理论，提出了基于要素禀赋差异的Hechscher-Ohlin模型。该模型假设，各国倾向于出口更多使用其相对丰富的要素的商品，进口更多使用其相对稀缺的要素的商品。H-O模型还预测了贸易对要素价格的影响，即要素价格均等化定理，指出国际贸易会使各国获得均等的同质要素的相对和绝对收益。 ³ 然而，在对现实的考察中，人们发现H-O理论与实际情况不一致，导致了列昂惕夫之谜。列昂惕夫之谜的成因探索过程本身就成为战后国际贸易理论发展的转折点和推动力。 ⁴

3.Brief Description of Intra-Industry Trade
3.产业内贸易概述

3.1 Definition of Intra-Industry Trade
3.1产业内贸易的定义

Intra-Industry Trade (IIT) refers to the exchange of goods or services with differentiated characteristics between different countries within the same industry. In intra-industry trade, countries or regions are both exporters and importers, and the products traded may be different, but they belong to the same industry category. This form of trade usually takes place in industries with a high level of technology and a high degree of specialization.
产业内贸易是指不同国家之间在同一产业内进行的具有差异化特征的商品或服务的交换。在产业内贸易中，国家或地区既是出口国又是进口国，交易的产品可能不同，但属于同一产业类别。这种形式的贸易通常发生在技术水平高、专业化程度高的行业。

This trade pattern contrasts sharply with traditional inter-industry trade. The latter is based on the principle of comparative advantage, emphasizing that countries focus on commodity production in specific industries according to their own resource endowments and production efficiency. In inter-industry trade, countries tend to export goods in which they have a comparative advantage while importing goods in which they have a comparative disadvantage. For example, a country may concentrate on exporting textiles while importing machinery and equipment. This trade pattern emphasizes the exchange of goods or services between different industries.
这种贸易模式与传统的产业间贸易形成鲜明对比。后者以比较优势原则为基础，强调各国根据自身资源禀赋和生产效率，侧重于特定行业的商品生产。在产业间贸易中，各国倾向于出口具有比较优势的商品，同时进口具有比较劣势的商品。例如，一个国家可能集中出口纺织品，而进口机械和设备。这种贸易模式强调不同行业之间的商品或服务交换。

However, in the context of globalization and technological progress, the rise of intra-industry trade reveals more complex trade relationships in modern economies. The core of intra-industry trade is that it occurs between countries that produce similar or related products. These products differ in quality, technology, brand, taste or other characteristics to meet the needs of different consumer groups. For example, trade between Germany and Japan, which both produce cars but have distinct brands and models, is an example of intra-industry trade. This trade is driven by consumer demand for diversified and differentiated products.
然而，在全球化和技术进步的背景下，产业内贸易的兴起揭示了现代经济中更为复杂的贸易关系。产业内贸易的核心是发生在生产类似或相关产品的国家之间。这些产品在质量、技术、品牌、口味或其他特点上各不相同，以满足不同消费群体的需求。例如，德国和日本都生产汽车，但有不同的品牌和型号，这两个国家之间的贸易就是产业内贸易的一个例子。这种贸易是由消费者对多样化和差异化产品的需求驱动的。

3.2 Types of Intra-IndustryTrade
3.2产业内贸易的类型

In the theory of intra-industry trade, goods that meet the standards for intra-industry trade are divided into two categories: homogeneous goods and differentiated goods.⁵
在产业内贸易理论中，符合产业内贸易标准的商品分为同质商品和差异商品两大类。 ⁵

3.2.1 Intra-industry trade in homogeneous products
3.2.1同类产品的产业内贸易

Homogeneous products or identical products refer to products that can be completely replaced with each other, that is, products have high cross-elasticity of demand, and consumers have exactly the same consumer preferences for such products. However, the proportion of intra-industry trade of homogeneous products is relatively small. Influenced by market time and location, it usually appears in specific trade forms, such as cross-industry trade of bulk products between countries, seasonal trade, entrepot trade, trade dumping, government foreign trade intervention policy, intra-multinational company trade, etc.
同质产品或完全相同的产品是指可以完全相互替代的产品，即产品具有很高的需求交叉弹性，消费者对这类产品具有完全相同的消费偏好。但是，同质产品的产业内贸易占比较小。受市场时间和地点的影响，通常以特定的贸易形式出现，如国与国之间大宗产品的跨行业贸易、季节性贸易、转口贸易、贸易倾销、政府对外贸易干预政策、跨国公司内部贸易等。

3.2.2 Intra-industry trade in heterogeneous products
3.2.2异质产品的产业内贸易

Compared to homogeneous products, heterogeneous products play a more significant role in intra-industry trade. Intra-industry trade involving heterogeneous products refers to the exchange of goods that are similar but not identical and cannot fully substitute for each other. These products have lower cross-elasticity of demand compared to homogeneous products and can be further categorized into three types: horizontally differentiated products, vertically differentiated products, and technologically differentiated products.⁶
与同质产品相比，异质产品在产业内贸易中的作用更为显著。涉及异质产品的产业内贸易是指相似但不完全相同且不能完全替代的商品的交换。与同质产品相比，这些产品的需求交叉弹性较低，可进一步分为三种类型：横向差异化产品、纵向差异化产品和技术差异化产品。 ⁶

(1)Horizontally Differentiated Products
（1）横向差异化产品

Homogeneous products share some common attributes, but different combinations of these attributes create distinctions among them, known as horizontal differences. ⁷The intra-industry trade of these products is largely influenced by consumer preferences. On the consumption side, as income levels rise, people tend to have more diverse demands for goods. On the production side, firms often produce products that differentiate themselves from competitors in order to expand their market share or compete effectively. This type of differentiation is common in industries such as tobacco, cosmetics, and clothing.
同质产品具有一些共同的属性，但这些属性的不同组合会在它们之间产生差异，称为横向差异。 ⁷ 这些产品的产业内贸易在很大程度上受到消费者偏好的影响。在消费方面，随着收入水平的提高，人们对商品的需求往往更加多样化。在生产方面，企业往往生产与竞争对手不同的产品，以扩大市场份额或有效竞争。这种差异化在烟草、化妆品和服装等行业很常见。

(2)Vertically Differentiated Products
（2）垂直差异化产品

Vertical differences refer to differences in product quality. In order to capture market share, continuous improvement in product quality is necessary, but not all consumers within a country may seek expensive high-quality products. Therefore, in addition to exporting high-quality products, a country may also import some lower-quality products of the same kind from other countries, leading to intra-industry trade. For instance, developed countries may focus on producing high-end, high-tech products, while developing countries may produce lower-cost, more affordable products. This division of labor based on quality levels allows consumers with varying income levels to find products that meet their needs and budgets. This type of differentiation is common in the automotive industry.
纵向差异是指产品质量的差异。为了占领市场份额，必须不断提高产品质量，但不是一个国家的所有消费者都可能寻求昂贵的高质量产品。因此，一个国家除了出口高质量的产品外，也可能从其他国家进口一些质量较低的同类产品，从而导致产业内贸易。例如，发达国家可能侧重于生产高端、高科技产品，而发展中国家可能生产成本较低、价格较低的产品。这种基于质量水平的劳动分工使不同收入水平的消费者能够找到满足他们需求和预算的产品。这种差异化在汽车行业很常见。

(3)Technologically Differentiated Products
（3）技术差异化产品

Technological differences refer to distinctions brought about by the emergence of new products. When similar products at different stages of their lifecycle are produced in various types of countries, leading to trade through imports and exports, intra-industry trade is generated. Technologically advanced countries continuously develop new products, while technologically less advanced countries primarily produce products where the technology is already mature. This difference is common in industries such as electronics and pharmaceuticals. Some scholars also categorize technologically different products as vertical differentiation products.⁸
技术差异是指新产品的出现所带来的差异。当处于生命周期不同阶段的类似产品在不同类型的国家生产，导致通过进出口进行贸易时，就产生了产业内贸易。技术先进的国家不断开发新产品，而技术不太先进的国家主要生产技术已经成熟的产品。这种差异在电子和制药等行业很常见。一些学者也将技术差异产品归类为纵向差异产品。 ⁸

4.Causes of Intra-Industry Trade
4.产业内贸易的成因

4.1 Product Differences: Product Heterogeneity Theory
4.1产品差异：产品异质性理论

The formation of intra-industry trade is based on specific conditions that the goods must satisfy, namely that they stem from the same industry, have similar production factor inputs, and possess mutually substitutable usage functions.⁹As previously discussed, intra-industry trade involves homogeneous products and heterogeneous products, with the heterogeneous products further divided into horizontal differences, vertical differences, and technological differences.
产业内贸易的形成是建立在商品必须满足的特定条件之上的，即它们来自同一产业，具有相似的生产要素投入，具有相互替代的使用功能。 ⁹ 如前所述，产业内贸易包括同质产品和异质产品，异质产品又分为水平差异、垂直差异和技术差异。

Horizontal difference products reflect consumers' demand for product diversity, prompting different countries to produce products with distinct characteristics. Vertical difference products reveal consumers' varying demands for product quality and grade, leading to different countries producing products of varying quality levels based on their comparative advantages. Technology difference products, on the other hand, demonstrate the impact of technological innovation and product lifecycle, enhancing international technological exchanges and industrial upgrades.
横向差异产品反映了消费者对产品多样性的需求，促使不同国家生产具有鲜明特色的产品。纵向差异产品反映了消费者对产品质量和档次的不同要求，导致不同国家根据比较优势生产不同质量水平的产品。另一方面，技术差异产品展示了技术创新和产品生命周期的影响，促进了国际技术交流和产业升级。

4.2 Consumer Preference Differences: Preference Similarity Theory
4.2消费者偏好差异：偏好相似理论

Preference Similarity Theory, also known as Overlapping Demand Theory, was proposed by the Swedish economist Staffan B. Linder in his 1961 paper On Trade and Transformation. This theory is often used to explain the mechanism of intra-industry trade between countries with similar levels of development.
偏好相似理论，又称重叠需求理论，由瑞典经济学家斯塔凡B提出。林德在1961年的论文《论贸易与转型》中写道。这一理论经常被用来解释发展水平相似的国家之间的产业内贸易机制。

The theory has two key assumptions: the assumption of different demand structures and the assumption of overlapping demand. ¹⁰From a supply perspective, firms will determine their production direction based on demand structures arising from consumer income differences. Products with the highest domestic demand, known as representative demand products, will be produced by firms. If domestic production exceeds domestic demand, firms will seek to export the surplus.
该理论有两个关键假设：不同需求结构假设和重叠需求假设。 ¹⁰ 从供给的角度来看，企业将根据消费者收入差异所产生的需求结构来决定其生产方向。国内需求最大的产品，即代表性需求产品，将由公司生产。如果国内生产超过国内需求，企业将寻求出口盈余。

The preference similarity theory leads to two main points: First, the domestic demand for a product determines its export potential, and economies of scale make representative demand products internationally competitive. Second, the more similar the demand structures of countries, the more their supply structures tend to converge. This leads to an increase in the overlap between demand and supply, consequently boosting the volume of imports and exports, and raising the level of intra-industry trade.
偏好相似理论主要有两点：一是产品的国内需求决定其出口潜力，规模经济使代表性需求产品具有国际竞争力。其次，各国的需求结构越相似，其供给结构就越趋于趋同。这导致需求和供应之间的重叠增加，从而增加了进出口量，提高了产业内贸易水平。

As shown in the Fig. 4.1, the horizontal axis represents per capita income, the vertical axis represents commodity grade, and MN represents the relationship between a country's commodity grade and per capita income, that is, as the per capita income level increases, the higher the consumer demand for commodity grade.
如图4.1所示，横轴代表人均收入，纵轴代表商品等级，MN代表一个国家的商品等级与人均收入的关系，即随着人均收入水平的提高，消费者对商品等级的需求也越高。

Fig. 4.1 Similar demand preferences lead to the formation of intra-industry trade¹¹
图4.1相似的需求偏好导致产业内贸易的形成 ¹¹

4.3 Firm Differences: Economies of Scale Trade Theory
4.3企业差异：规模经济贸易理论

Economies of scale trade theory was developed by Paul R. Krugman. In the early 1980s, economists such as Krugman proposed to go beyond the assumptions of perfectly competitive markets and constant returns to scale in traditional international trade theory. This theory explains the new changes of trade pattern from the empirical point of view.
规模经济贸易理论是由保罗·R.克鲁格曼20世纪80年代初，克鲁格曼等经济学家提出超越传统国际贸易理论中完全竞争市场和规模报酬不变的假设。该理论从实证的角度解释了贸易格局的新变化。

The assumptions underlying intra-industry trade include the following: from a static perspective, analyzing imperfectly competitive markets in the economy with economies of scale, while considering differences in demand. Krugman first demonstrated that economies of scale can lead to the occurrence of intra-industry trade, and this trade pattern represents a complete form of intra-industry trade. Furthermore, Krugman also pointed out that the presence of trade costs and the domestic market size effect imply that countries tend to develop products with the highest domestic demand to gain the advantage of economies of scale.
产业内贸易的基本假设包括：从静态的角度，分析具有规模经济的经济体中的不完全竞争市场，同时考虑需求的差异。克鲁格曼首先论证了规模经济可以导致产业内贸易的发生，这种贸易模式代表了产业内贸易的完整形式。此外，克鲁格曼还指出，贸易成本和国内市场规模效应的存在，意味着各国倾向于开发国内需求最大的产品，以获得规模经济的优势。

Furthermore, Paul R. Krugman and Helpman E. established a model with two countries and two industries - Industry X (characterized by product heterogeneity, increasing returns to scale, and monopolistic competition) and Industry Y (homogeneous products, constant returns to scale, and perfect competition) - to analyze intra-industry trade, as illustrated in Figure 4.2. Capital and labor are identical and freely mobile between industries. Their research indicates that free trade can achieve integration equilibrium; the extent of intra-industry trade depends on the similarity of factor endowments between countries and the market size of capital-abundant nations.
此外，Paul R. Krugman和Helpman E.我建立了一个模型，包括两个国家和两个行业--X行业（以产品异质性、规模报酬递增和垄断竞争为特征）和Y行业（产品同质、规模报酬不变和完全竞争）--来分析行业内贸易，如图4.2所示。资本和劳动力是同一的，在产业间可以自由移动的。他们的研究表明，自由贸易可以实现一体化均衡;产业内贸易的程度取决于各国要素禀赋的相似性和资本富裕国家的市场规模。

Fig. 4.2 The generation of intra-industry trade under economies of scales^⑪
图4.2规模经济下产业内贸易的产生 ^⑪

5.Characteristics of Intra-Industry Trade
5.产业内贸易的特点

Summarizing the above discussion on intra-industry trade, the following characteristics of intra-industry trade can be identified.
综合以上关于产业内贸易的讨论，可以确定产业内贸易的以下特征。

(1) Intra-industry trade involves the mutual exchange of similar products within the same industry, rather than the exchange of dissimilar products between industries.
(1)产业内贸易是指同一产业内同类产品的相互交换，而不是不同产业之间不同产品的交换。

(2) The flow of products in intra-industry trade is bi-directional, meaning products within the same industry can be exchanged between two countries.
(2)产业内贸易的产品流动是双向的，即同一产业内的产品可以在两国之间进行交换。

(3) Products in intra-industry trade are diverse. These products include both capital-intensive and labor-intensive goods, as well as high-tech and standard-tech products.
(3)产业内贸易的产品是多样化的。这些产品既包括资本密集型产品和劳动密集型产品，也包括高技术产品和标准技术产品。

(4) Goods in intra-industry trade must meet two conditions: they must be substitutable in consumption and require similar or identical factors of production in their production.
(4)产业内贸易中的商品必须满足两个条件：它们必须在消费中具有可替代性，并且在生产中需要相似或相同的生产要素。

At the same time, it is important to note that intra-industry trade exhibits characteristics distinct from inter-industry trade¹²:
与此同时，重要的是要注意，产业内贸易表现出与产业间贸易不同的特征 ¹² ：

(1) The pattern of intra-industry trade is unpredictable.
(1)产业内贸易的模式是不可预测的。

(2) The relative importance of intra-industry trade versus inter-industry trade depends on the similarities between countries.
(2)产业内贸易与产业间贸易的相对重要性取决于各国之间的相似性。

6. Case Study: Trade of Chinese Characteristic Oil Crop Industry
6.中国特色油料作物产业贸易案例分析

6.1 Industry Introduction
61行业介绍

The distinctive Chinese oil crop industry, including sunflower seeds, sesame, and sesame seeds, has gained a foothold in global trade in recent years. According to research by Li Xiaozhong and others, over the past two decades, trade in the Chinese oil industry has primarily been inter-industry trade, but there has also been a noticeable trend towards intra-industry trade. The presence of intra-industry trade not only reflects the diversified demand in China's oil crop industry but also underscores China's competitiveness in the global oil crop market.
近年来，独特的中国油料作物产业，包括向日葵籽、芝麻和芝麻籽，在全球贸易中站稳了脚跟。根据李晓忠等人的研究，近20年来，中国石油行业的贸易主要是产业间贸易，但也出现了明显的产业内贸易趋势。产业内贸易的存在不仅反映了中国油料作物产业需求的多样化，也凸显了中国在全球油料作物市场上的竞争力。

Fig. 6.1 Foreign trade of specialized oil seeds in China during 2001 to 2018¹³
图6.1 2001 - 2018年中国特种油料种子对外贸易情况 ¹³

6.2 Trade Characteristics

From the statistical data, trade characteristics of China's oil crop industry can be analyzed quantitatively through several kinds of indexes. Scott et al.¹⁴ took the lead in systematic research on intra-industry trade and put forward GL index method to measure intra-industry trade level from static perspective.Bruelhart proposed the marginal intra-industry trade index (BI index) in 1994¹⁵, and Thom and McDowell proposed the marginal intra-industry trade type measurement index in 1999¹⁶
从统计数据中可以通过多种指标对我国油料作物产业的贸易特征进行定量分析。Scott等 ¹⁴ 率先对产业内贸易进行了系统研究，提出了从静态角度衡量产业内贸易水平的GL指数方法，Bruelhart于1994年提出了边际产业内贸易指数（BI指数） ¹⁵ ，Thom和McDowell于1999年提出了边际产业内贸易类型衡量指数 ¹⁶ .

Table 6.1 Thom&McDowell index of specific oilseed crops¹⁷
表6.1特定油料作物的Thom&McDowell指数 ¹⁷

According to Thom&McDowell marginal intra-industry trade type index, the marginal horizontal intra-industry trade index (BI) of China's characteristic oil from 2001 to 2021 is 0.108, while the marginal vertical intra-industry trade index (HI) is 0.486. This indicates that the increase of intra-industry trade in China's oil crop industry mainly comes from vertical intra-industry trade, that is, trade between products of the same kind but different quality.
根据Thom&McDowell边际产业内贸易类型指数，2001 - 2021年中国特色油边际水平产业内贸易指数（BI）为0.108，边际垂直产业内贸易指数（HI）为0.486。这表明，中国油料作物产业内贸易的增长主要来自垂直型产业内贸易，即同类但质量不同的产品之间的贸易。

6.3 Analysis of regression results of influencing factors
6.3影响因素回归结果分析

Li Xiaozhong and Ma Chunrui measured GL index of China and related countries according to the above measurement method and took it as explanatory variable. In this paper, three influencing factors, consumer preference difference (CPD), product difference (PD) and market size difference (DGDP), were selected as explanatory variables for panel Tobit regression analysis.
李晓忠、马春瑞按照上述测算方法测算了中国及相关国家的GL指数，并将其作为解释变量。本文选取消费者偏好差异（CPD）、产品差异（PD）和市场规模差异（DGDP）三个影响因素作为面板Tobit回归分析的解释变量。

Table 6.2 Regression results of factors influencing intra-industry trade of specific oilseed crops between China and trading partner countries^⑰
表6.2中国与贸易伙伴国特定油料作物产业内贸易影响因素回归结果 ^⑰

6.3.1 Consumer Preference Differences
6.3.1消费者偏好差异

Consumer preference differences have exhibited a negative effect in intra-industry trade within the specialty oilseed industry, significantly affecting sunflower seed trade at the 1% level. This indicates that consumer preference differences play a restraining role in intra-industry trade of sunflower seeds between China and its trading partners. The more similar consumer preferences are, the more similar the consumption structure, leading to the promotion of bilateral intra-industry trade in sunflower seeds. However, the impact of consumer preference differences on sesame and sesame seed intra-industry trade is not significant.
消费者偏好差异对特种油料行业内的产业内贸易产生了负面影响，对向日葵籽贸易产生了1%的显著影响。这表明消费者偏好差异对中国与贸易伙伴国的向日葵籽产业内贸易具有抑制作用。消费者偏好越相似，消费结构越相似，从而促进了双边向日葵籽产业内贸易。但消费者偏好差异对芝麻及芝麻籽产业内贸易的影响并不显著。

6.3.2 Product Differences
6.3.2产品差异

Product differences have shown a positive effect on overall specialty oilseed intra-industry trade, significant at the 10% level. They significantly promote intra-industry trade in sunflower seeds, sesame, and sesame seeds, indicating that greater differences in specialty oilseed production between countries at different technological levels are conducive to the development of bilateral intra-industry trade.
产品差异对整体特种油料种子产业内贸易产生了积极影响，在10%的水平上显着。它们显著促进了向日葵籽、芝麻和芝麻籽的产业内贸易，表明不同技术水平的国家之间在特种油料生产方面的较大差异有利于双边产业内贸易的发展。

6.3.3 Market Size Differences
6.3.3市场规模差异

Market size differences do not have a significant impact on overall specialty oilseed intra-industry trade and show both positive and negative effects. When analyzing different varieties, market size differences exhibit a restraining effect on intra-industry trade in sunflower seeds, significant at the 10% level. This suggests that in the international market for sunflower seeds, the smaller the market size differences between countries and the more similar the resource endowment, the stronger the promotion of intra-industry trade in sunflower seeds between the two countries. ¹⁸In contrast, they show a promoting effect in intra-industry trade of sesame seeds, significant at the 1% level, indicating that larger market size differences in the international sesame trade market will provide more differentiated products, thereby promoting the development of intra-industry trade in sesame seeds.
市场规模差异对特种油料种子产业内贸易的总体影响不显著，并表现出积极和消极的影响。在分析不同品种时，市场规模差异对向日葵籽产业内贸易有抑制作用，在10%的水平上显著。这表明，在向日葵籽国际市场上，各国市场规模差异越小，资源禀赋越相似，对两国向日葵籽产业内贸易的促进作用越强。 ¹⁸ 相反，它们对芝麻产业内贸易表现出促进作用，在1%的水平上显著，表明国际芝麻贸易市场上较大的市场规模差异将提供更多差异化产品，从而促进芝麻产业内贸易的发展。

6.4 Conclusions and Recommendations
6.4结论和建议

The practice of Chinese characteristic oil industry shows that intra-industry trade is an important force to promote industrial upgrading and meet diversified needs. Through in-depth analysis and understanding of the characteristics and influencing factors of intra-industry trade, China can better position itself in global trade and promote economic transformation and sustainable development. In the future, China should continue to utilize its intra-industry trade potential to enhance its competitiveness in the global oil market through technological innovation and market diversification.
中国特色石油产业的实践表明，产业内贸易是推动产业升级、满足多样化需求的重要力量。通过深入分析和了解产业内贸易的特点和影响因素，中国可以更好地在全球贸易中定位，促进经济转型和可持续发展。未来，中国应继续利用其产业内贸易潜力，通过技术创新和市场多元化来提高其在全球石油市场的竞争力。

7.Discussion and Conclusion
7.讨论和结论

This paper probes into the theoretical basis, definition, types, causes of Intra-Industry Trade and its influence on modern international trade. It is found that intra-industry trade is a reflection of complex trade relations in modern economy under the background of globalization and technological progress. It involves the mutual trading of different products within the same industry and is closely related to product differentiation, technological progress and diversity of consumer preferences. The case study of China's characteristic oil crop industry reveals the key role of intra-industry trade in promoting industrial upgrading and meeting diversified needs. In addition, this paper identifies the main factors affecting intra-industry trade, including differences in consumer preferences, product differences and market size differences.
本文探讨了产业内贸易的理论基础、定义、类型、成因及其对现代国际贸易的影响。研究发现，产业内贸易是在全球化和技术进步的背景下，现代经济中复杂贸易关系的反映。它涉及同一行业内不同产品的相互交易，与产品差异化、技术进步和消费者偏好的多样性密切相关。中国特色油料作物产业的案例研究揭示了产业内贸易在促进产业升级和满足多样化需求方面的关键作用。此外，本文还确定了影响产业内贸易的主要因素，包括消费者偏好差异、产品差异和市场规模差异。

Comprehensive analysis of the full text, we can draw a conclusion that intra-industry trade is an indispensable part of the global economy and has a profound impact on economic development and international trade. ¹⁹China should continue to utilize the potential of its intra-industry trade to enhance its international competitiveness through the following measures: improving the level of effective domestic supply, implementing differentiated development strategies, strengthening anti-risk capabilities, and coordinating industrial and trade policies to ensure industrial security and promote healthy and sustainable development.²⁰ Through these recommendations, China can better position itself in global trade and promote economic transformation and sustainable development..
综合分析全文，我们可以得出这样一个结论：产业内贸易是全球经济不可或缺的组成部分，对经济发展和国际贸易都有着深远的影响。 ¹⁹ 中国应继续发挥产业内贸易潜力，通过提高国内有效供给水平、实施差异化发展战略、增强抗风险能力、协调产业政策和贸易政策等措施提升国际竞争力，保障产业安全，促进健康可持续发展。 ²⁰ 通过这些建议，中国可以更好地在全球贸易中定位，促进经济转型和可持续发展。

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