As we all know, the islands in the South China Sea have always been Chinese territory. However, forasmuch as the influence of international politics and world pattern after the Cold War, the ambiguity of the South China Sea issue after World War II in documents such as the " Cairo Declaration " San Francisco Peace Treaty with Japan " has laid a foreshadowing for the South China Sea dispute. This paper takes China's policy on the South China Sea issue as the object of analysis, focusing on finding the impact of China's policy on that issue on the shaping of the history of the South China Sea, aiming to explain the background, reasons, conditions and impact of China's sea power strategy adjustment during 1949-1978. In order to achieve the above objectives, the author mainly uses game theory analysis method, historical literature analysis method and case analysis method to carry out research, and makes a qualitative analysis of the influence of China's policy on the history of the South China Sea during 1949-178. The research results show that the influence of China's policy on the history of the South China Sea is mainly divided into two stages: declaration of sovereignty and military rights protection