In post financial crisis period, the regional economic cooperation mechanism among China, Japan and South Korea reaches a new development stage, as a result, the international investment agreement among China, Japan and South Korea is signed and it is possible to build a free trade zone among the three countries. This paper studies total trade quantity and trade products structure in the regions of the three countries based on trade data of the three countries in a long time during 19922011, and emphatically studies FTA trade flow rate and development potential among the three countries by using expansive trade gravity model. The empirical research conclusion is of important significance to accelerating the construction of free trade zone among China, Japan and South Korea and to promoting economic and trade cooperation level of the three countries. 