The South China Sea, along with the Korean Peninsula and the Taiwan Strait, is described as one of the three hotspots in East Asia because of its potential for conflict of interest and threat to peace and security. Therefore, the issue of its borders is of international importance. As a quasi-closed sea, it is home to numerous small islands and cliffs, as well as abundant living and non-marine reserves, as well as providing key maritime routes for commercial navigation. For these reasons, the sea has become the target of conflict between coastal countries and its neighbors. In this sea, the main issues in dispute are: 1- Border disputes over the determination of the lines of origin, the boundaries of the territorial seas and also the exclusive economic zone2. Territorial disputes over several islands, including the Paracel and Spratly archipelagos. Because of its superior power, as well as some unproven historical claims, China sets the nine-dash as the final line of its sovereignty, some of which extend as far as the coastal sea. The United States and the countries bordering the South China Sea strongly oppose this, as well as China's historic claims. The littoral states of the South China Sea consider the historic claims and the nine-dash claimed by the Chinese government to be contrary to the laws of the UN Convention. The United States, as a trans-regional player, also provides diverse support to coastal countries. In this research, with a descriptive analytical approach and using new sources, the disputed issues between the claiming countries have been studied and the role of the United States in terms of geopolitical competition has been analyzed.