The CIIE has made the Chinese market a shared market for the world. Starting from the fundamental difference between past trade protection theories and policy propositions and the continuous hosting of the CIIE. Author: Sang Baichuan (Dean of the Institute of International Economics at the University of International Business and Economics). In 2018, China officially opened the world's first national level exhibition and import expo with an import theme, which has been held for six times. Continuously holding China International Import Expo, actively expanding imports of goods and services, promoting investment and trade cooperation, providing more export and economic cooperation development opportunities for countries around the world, allowing the world to share the opportunities of China's large market, promoting mutual benefit and win-win situation, and conveying a strong signal of support for economic globalization and multilateralism to the world. It is a powerful obstacle to the reverse flow of globalization and also injects certainty into the fragile world economy, It demonstrates China's firm determination to promote high-level openness and build an open world economy. Throughout the history of world economic development, there are few trade policy proposals and national practices that actively expand imports in the world. In stages of rapid economic growth and smooth development, free trade advocates will prevail; When the world economy enters a depression or stagnation, the advocacy of trade protection will rise. Countries in a leading economic position often advocate for free trade; Countries that are relatively vulnerable often strengthen trade protection. The opposing movement of freedom and protection, two trade theories and policies, runs through the development history of international trade theory. In the current environment of global economic downturn and rising uncertainty, global trade protectionism is on the rise, imposing tariffs and restricting imports have become policy choices for some countries; As a developing country, China has continued to hold import expos and actively expanded imports under the conditions of slowing economic growth and increasing downward pressure. This is a pioneering move, providing a new practice for international trade and a significant innovation in international trade theory. The "naive industry protection theory" proposed by Hamilton in the United States at the end of the 18th and early 19th centuries and improved by Liszt in Germany, as the earliest basic theory of trade protectionism, became a theoretical weapon for the United States and Germany, which were in the process of development, to resist and resist the strong overseas expansion of British industrial capital. The theory of infant industry protection suggests that a country should choose certain infant industries with potential comparative advantages and development prospects, provide appropriate and temporary tariff protection, and restrict imports in order to gradually support its international competitiveness. In the early stages of protection, production costs are high and consumers have to pay higher prices. Once these immature industries grow and production costs decrease, consumers will benefit from the price drop, and trade protection measures can be abolished at that time; If not protected in the early stages of the creation of emerging industries, fragile and immature industries are prone to premature death under strong international competitive pressure. The proposition of the "theory of protecting infant industries" aims to assist developing countries in the independent development of infant industries. However, if protectionism prevails and all countries want to develop new industries that other countries already have comparative advantages, they will fall into the trap of protectionism, and in the process of economic cooperation among fragmented countries, the development of each country is generally slow. In fact, the more effective way to promote the transfer of comparative advantage is not through trade protection or import restrictions, but through international technology transfer, international capital flow, and economic growth