In traditional times of East Asia, China, Korea, Japan, Vietnam, Okinawa formed ＂All under heaven＂. Korean king needs Chinese emperor's Installation to be recognized as the legitimate king. However, how much influence does china have over Korea? On this discussion, the 15th king of Choson Dynasty-- Gwanghaegun is an important case. This article focuses on how Gwanghaegun has gained the throne and why he has loos it. We find three factors affect the Korean people agree with the right to rule, and to explore the order of importance. Conclusion that ＂China canonized＂ is relatively unimportant, ＂ability to govern＂ is important, ＂the Confucian ethics＂ is most important.