The United States’ financial crisis and the rapid development of China caused the change of the international environment in East Asia，the decreasing leadership ability of the United States and the weakening will of the rising countries to abide by the international standard caused the instability of the international order. This paper analyzes the new international environment and the influence on the Korean peninsula security structure and the relationship between China and ROK. The contradiction between China and South Korea relationship is not so much come from the recognition of bilateral relations but from the constrain of the new East Asia international environment. It is necessary for China and South Korea to consider these factors comprehensive when they try to improve the relations between them and the relations between ROK and DPRK.