With the continuous development of northeast Asian integration, the establishment of free trade zones between China, Japan and South Korea has become a development trend. This paper USES the GTAP model to simulate the changes and impacts brought by the reduction of agricultural tariffs in the free trade zones of China, Japan and South Korea on agricultural trade. The research results show that: first, the gradual reduction of tariff barriers for agricultural products of China, Japan and Korea will have a greater trade effect on China; Second, the creation effect of China-south Korea trade is far greater than that of China and Japan. Third, the reduction of agricultural tariffs will promote the growth of the overall economic aggregate of the three countries and change the terms of trade.