Abstract: As the three most active economies in economic and trade in East Asia, China, Japan and South Korea have great potential for economic cooperation. This paper uses the standard GTAP model to analyze the economic impact of tariff adjustment and trade facilitation on China, Japan and South Korea. The study found that in the case of single tariff reduction, China's GDP and social welfare utility were negatively affected, most of the industrial output of China and South Korea showed growth, while the output of many sectors in Japan was negatively impacted; In the case of single promotion of trade facilitation or the superposition of two trade policies, regional economic cooperation has promoted the economic growth of the three countries, expanded the scale of intra-regional trade, and improved the terms of trade of the three countries. Therefore, in regional economic cooperation, we should promote the negotiation process of the China-Japan- South Korea Free Trade Zone in stages, accelerate the optimization and upgrading of China's own industrial structure, and strive for tariff concessions of Japan and South Korea on Chinese agricultural products and processed agricultural products.