With the strength of economic competition and connection in the world, the globalization and regional economic integration have become the most important feature in the world since 1990's. Economics regional integration organizations continue to emerge and develop, such as the European Union, NAFTA and ASEAN and so on. Their enlargement processes speed up and they form the wide range of regional integration organizations. This encourage many countries to participate in the existed organization or build a new one. The economy of South Korea, China and Japan is the strongest in the East Asia and if the economic integration of the three countries was builded, it would be a significant role which can promote economic development of the three countries. This is a large market that own nearly 1.5 billion consumers, GDP of 7000 billion dollars and nearly 2000 billion dollars trade volume. The economic complementarily of the three countries, geographical proximity and the common human environment are the advantages to promote the economic integration of the three countries. However, there are some obstacles such as historical issues, political mutual trust, the leading country issues and the economic competitiveness of the three countries affect the development of the three countries' economic integration. The economic integration of the three countries is inevitable, but it requires a long-term gradual process. How to achieve the economic integration of the three countries is the key issue. This article analyzes the potential affects of the South Korea, China, and Japan FTA using the trade competitiveness index, discusses the possibility to establish the South Korea, China, and Japan FTA using the trade complementarity index, and proposes a solution for promoting the South Korea, China, and Japan FTA. Firstly, we analyzes the trade competitiveness in the seven main fields of the three countries using the trade competition index. Overall, our analysis shows that the three countries have the competitiveness in the basic commodity field, the South Korea and China have the competitiveness of the capital intensive products and the China and Japan have the competitiveness of the labour intensive products. So we can reduce cooperation in these fields during negotiation of the South Korea, China, and Japan FTA. Secondly, we analyzes the trade complementarity in the seven main fields of the three countries using the trade complementarity index. Overall, our analysis shows that South Korea can export the capital intensive products to China and import the labour intensive products from China. Japan can export the capital intensive products to South Korea. China can import the capital intensive products from South Korea and export the labour intensive products to Japan. Finally, We examines whether a bilateral FTA paves the way for multilateral free trade(MFT) among the South Korea, China and Japan based on GTAP simulation results, and then considers what are the feasible paths in a dynamic game model. The main conclusions are as follows: A bilateral FTA between China and Japan will not be formed initially. If South Korea-Japan FTA completes initially, it will expand through the acceptance of China and be a building block for South Korea-China-Japan FTA, even if South Korea-China FTA will not lead to MFT via Japan's participation. The expansion of South Korea-China FTA or South Korea-Japan FTA through overlapping trade agreements allows the option of hub-and-spoke systems and achieves MFT, except when Japan acts as a hub country. South Korea-China FTA was established and then consider launching the FTA negotiations with Japan according to the process of Japan -Korea FTA negotiations. So we found that it is better to promote Japan -Korea FTA firstly.