With the end of the Cold War, there are getting more and more international economic cooperation among countries. In the late 1990s, the East Asian countries attempts to let their economic cooperation go further and further, hoping to promote trade within the region in order to enhance the benefits of trade liberalization. However, compare with Europe and North America, the East Asian economic cooperation is lagged behind them, especially economic cooperation in Northeast Asia. There are Asia Pacific Economic Cooperation (APEC), ASEAN Free Trade Area and ASEAN plus three rights now. However, China, Japan and South Korea in Northeast Asia as the strongest economies and the most representative of the countries, it has not been further integration. This paper is tried to investigate the possibility of forming a trilateral free trade area among China, Japan and South Korea. And this article is tried to find out what is the key elements affecting these countries' economic cooperation by the neo-realism perspective.