二次世界大戰結束後，以美國為首的民主國家採取長期的對蘇聯的社會主義國家圍堵不接觸的「冷戰」作為，此種兩極體系發展產生一種軍備競賽方式取代戰爭模式，1991年蘇聯共產體制瓦解，原已經於一九八九年宣告結束的東西「冷戰」正式結束，冷戰結束後，世界軍事格局脫離了兩極對峙，1978年鄧小平掌權後，判斷世界新形勢，修正社會主義路線，經濟上遂行改革開放政策，帶動了中共國力崛起。 崛起的中共在軍事上不斷現代化，威脅著南海爭議相關國家，同時也代表美國在亞洲的利益受到挑戰，中共近期將南海島礁主權列為國家重大利益，軍力部署轉向海洋及東南方，也使中國威脅論升高，導致東協部份國家紛紛加強軍備，增加亞太地區的不穩定性，促使東協國家引進美國力量介入。 美國持續在東亞地區透過雙邊同盟或軍事關係，維持美國的國家利益，美國第44任總統歐巴馬也以重返亞洲為國務外交重大政策，因此美國與中共兩國在亞洲地區的合作或競爭作為，未來將左右南海爭議走向，這也是南海問題複雜的原因。 南海領土主權爭議是二戰結束後，亞洲國家戰後紛紛掙脫殖民國控制，先後完成各種制度的國家獨立開始，另外1952年國際海洋法公佈領海及鄰接區公約，也喚起世界各海洋國家的重視，然而國際法著重現實主義立場，使得南海周邊各國莫不以島礁「先佔」（Occupation）的行為爭取國家利益。 本文以南海地區的情勢發展為基礎，探究中共與美國對南海的國家戰略，首先從國際海洋法論南海主權問題，接續再由政治外交、經濟貿易、軍事等戰略面向分析，最後比較兩個大國的戰略互動行為，以求更進一步認識南海問題。 / Since the end of WWII, the democratic countries which led by U.S. have been adopting a policy with isolating and encircling measures to against former USSR and its follower communist countries for more than 3 decades which known “Cold War”, instead of traditional warfare, the pattern of these two poles of the political bodies gradually developed another situation of armament competition, in 1991, the communist body of the Soviet has collapsed, it was also a formal declaration of the end of West-East confrontation which we called Cold War. Ever since the Cold War, the pattern of the military strategy has been changed, in 1978, under Deng, Xiao-Ping’ ruling, he re-aligned its original socialist route by judging reality of world environment and adopted open policies on the aspect of economy, this movement has caused China’s power rising. China’s rising continuously keeping PLA modernized militarily, that also caused significant threats to countries who involve the dispute of South China Sea issues, mean while, it represent that the U.S. interests in Asia have been challenged as well, China has claimed the sovereignty of isled of South China Sea as critical interests of PRC recently, the deployment of forces has been moved to south east of China and its coastal areas, this move has elevated the possibility which known as “theory of China’s threat” and relatively increased Pac-Asia regions unstable and caused armaments enforcement themselves, it also welcome US power involve by ASEAN. The US continuously intent to maintain it’ interests in South Asia through bi-lateral allies and military relations cooperation, the President Obama has announced that return to South Asia will be a significant policy for US, thus the competition between US and China in the area will affects the dispute among the countries and makes it more complex. The dispute of South China Sea sovereignty had started after WWII and countries which out of colonial controlled and had all their policies established, on the other hand, in 1952, the United Nations Convention on the Law of Sea (UNCLOS) issued has reminds and abstracts oceanic countries attention, however, international laws tend to reality, so that there is no country around the South China Sea without struggling for its own interests which by measure of pre-occupying isled on that. The context is base on the development of South China Sea as fundamentals so as to explore the strategies both US and PRC whom involved South China Sea disputes, first will start to discuss the problems of sovereignty base on international ocean laws, and then to discuss on analysis of various aspects such as political diplomacy, economic trade and military and will be wrapped up by the comparison of US-PRC on strategic interaction so as to make readers gain more understanding on the issues of South China Sea.