In the process of building a modern industrial system, there are three important development directions, namely intelligence, greenness, and integration, which are also important connotations of the construction of a modern industrial system. The Fourth Plenary Session of the 20th Central Committee of the Communist Party of China passed the "Proposal of the Central Committee of the Communist Party of China on Formulating the 15th Five Year Plan for National Economic and Social Development" (hereinafter referred to as the "Proposal"), which requires adhering to the focus of economic development on the real economy, adhering to the direction of intelligence, greenness, and integration, accelerating the construction of a manufacturing power, quality power, aerospace power, transportation power, and network power, maintaining a reasonable proportion of manufacturing industry, and building a modern industrial system with advanced manufacturing industry as the backbone. The two directions of intelligence and greenization are relatively easy to understand, which are directly related to the digital transformation and greenization transformation that China is currently facing. Integration is reflected in various aspects of economic, social, and industrial development, such as the integration of primary, secondary, and tertiary industries, the integration of advanced manufacturing and modern service industries, the deep integration of the real economy and digital economy, the deep integration of technological innovation and industrial innovation, and even urban-rural integration, military civilian integration, cultural and tourism integration, etc. The integration in the modern industrial system is mainly reflected in three aspects: firstly, efforts are made to promote the deep integration of advanced manufacturing and modern service industries, which is necessary for building a modern industrial system with advanced manufacturing as the backbone. The second is to focus on promoting the deep integration of the real economy and the digital economy, which is necessary to adhere to the principle of "putting the focus of economic development on the real economy and accelerating the construction of a modern industrial system supported by the real economy". Third, we should focus on promoting the deep integration of scientific and technological innovation and industrial innovation, which is required by "building a modern industrial system that is independent, controllable, safe, reliable and competitive, and then building a modern industrial system with integrity, progressiveness and security". At present, as China is promoting new industrialization and achieving high-quality development, integration is one of the important directions for building a modern industrial system, which has significant practical value. One is conducive to improving industrial economic efficiency and overcoming the "Baumol cost disease". The economic community refers to the phenomenon of an increase in the proportion of the service industry, which appears to optimize the economic structure on the surface, but actually leads to a decrease in overall social productivity as the "Baumol cost disease". This is mainly due to the difficulty in improving productivity in the service industry. At present, China's industrialization has been basically completed, and the service industry occupies a dominant position. In this situation, how to maintain the quality and efficiency of economic growth, and keep total factor productivity within a certain reasonable range, integration is an important way out. Integration, especially the development of advanced manufacturing and modern service industries, involves overlaying services on the basis of manufacturing to form a "manufacturing+service" model. This not only improves the quality of supply, but also enables differentiated competition, avoiding "blood buying" price competition between homogeneous products, effectively improving the profitability of enterprises, and promoting the overall production efficiency of the national economy, thus avoiding falling into the "middle-income trap". Secondly, it is conducive to the formation of new industries, new formats, and new models, promoting industrial upgrading, and enhancing the international competitiveness of industries. Integration, especially the deep integration of the real economy and the digital economy, has led to the widespread penetration of information technology, digital technology, and data elements into various aspects such as product design, customer customization, integrated manufacturing, marketing, supply chain management, quality management, testing and certification, forming a new real economy and significantly enhancing the competitiveness of China's manufacturing industry in the international market and its position in the global value chain. Thirdly, it is conducive to cultivating and developing new quality productive forces, enhancing the independent and controllable level of industrial and supply chains, and improving their ability to resist risks. Integration, especially in promoting the deep integration of technological innovation and industrial innovation, can help fill the gap in China's industrial technology system and promote the promotion and application of new knowledge and technologies. On the one hand, it can better transform and enhance traditional industries; On the other hand, it promotes the development and growth of emerging and future industries, and drives the development of new quality productivity. The deep integration of technological innovation and industrial innovation is an important guarantee for achieving dynamic innovation iteration and supporting industrial upgrading, which can significantly enhance the independent controllability and risk resistance of China's industrial and supply chains. The proposal places "building a modern industrial system and consolidating and strengthening the foundation of the real economy" as the first strategic task, indicating the importance of building a modern industrial system. Integration, as one of the important development directions of modern industrial system, must be given sufficient attention. During the 15th Five Year Plan period, the concept of integrated industrial development should be firmly established, and corresponding measures should be taken to vigorously promote it. One is to focus on promoting the servitization of manufacturing, especially the deep integration of advanced manufacturing and modern service industries. Since 2015, the proportion of China's service industry has exceeded 50%, and by 2024, the proportion of the service industry will reach 56.7%. It is a trend for the proportion of China's service industry to continue to rise in the future. How to consolidate and strengthen the foundation of the real economy while the proportion of the service industry increases, and steadily enhance the international competitiveness of the industry, the key is to avoid "premature and rapid deindustrialization" and not weaken the supporting position of the manufacturing industry in the construction of a modern industrial system. So, we need to take the path of service-oriented development in manufacturing, especially to promote the deep integration of advanced manufacturing and modern service industries. We should establish and improve a policy system that promotes the deep integration of advanced manufacturing and modern service industries from aspects such as land use, talent, technology, and finance, optimize the business environment for integrated development, enhance cross departmental policy coordination, and eliminate institutional and mechanism barriers to the integrated development of service and manufacturing industries. The second is to focus on promoting the deep integration of the real economy and the digital economy. We need to accelerate the construction of institutional mechanisms to promote the development of the digital economy, improve the policy system for promoting digital industrialization and industrial digitization, and promote the deep integration of real numbers. Deeply promote the "data element ×" "artificial intelligence+" action and implement the industrial Internet innovation and development project, enable thousands of businesses in all directions, constantly explore new industries, new models, and new formats for the integration of real and digital development, foster a digital transformation service ecosystem supported by technology, capital, talent, data and other factors, and fully demonstrate the combined effect of "digital+manufacturing+services". The third is to focus on promoting the deep integration of scientific and technological innovation and industrial innovation, and to implement the requirements of "coordinating the construction of national strategic scientific and technological forces, enhancing systematic research and development capabilities" and "improving the regional innovation system, laying out the construction of regional scientific and technological innovation centers and industrial scientific and technological innovation highlands, and strengthening the source function of international scientific and technological innovation centers" in the "Suggestions". Author: Guo Chaoxian (Director and Researcher of the Industrial Organization Research Office at the Institute of Industrial Economics, Chinese Academy of Social Sciences)