In recent years，China-Japan-South Korea（CJK） Trilateral Cooperation has become an integral and significant part of East Asian regional integration. Since 1999，the trilateral cooperation has experienced twists and turns and currently faces new opportunities and challenges. In retrospect，CJK cooperation embodies the characteristic of multi-layer，broad and high frequency. In the foreseeable future，the cooperation will be mainly influenced by common but differentiated strategic target and choice among the three countries，domestic politics such as public opinion and nationalism，and third-party factors especially impact from the U.S. How to take advantages，seek common grounds and realize inclusive development will determine the future CJK trilateral cooperation and even the East Asian regional integration as a whole.