It is a comprehensive and systemic study of the national question in Yugoslavia by the ways of several subjects. "Yugoslavia" that mentioned in the paper means the territory of the Socialist Federal Republic of Yugoslavia (SFRY) from 1945 to 1991.Yugoslavia is the convergent territory of different civilizations, so the national question is very important and complex. This paper focus on analyzing the cultural and institutional origins of the national crises in Yugoslavia, considering the interaction relationship between the history and reality, the domestic and international factors, trying to answer these questions: 1) Why did the nationalism become the persistent factor menacing and destroying the unity of nations in Yugoslavia? 2) What are the ultimate reasons of the misstep of League of Communists of Yugoslavia (LCY) dealing with the national question? 3) The national question in Yugoslavia and the international relation after the Cold War.The author's main views are listed following:The first, the whole Yugoslavia had divided into three parts: the Catholic Civilization in West Europe, the Orthodox Civilization of the Slav and the Islamic Civilization of the Turk from the 16th century. The differentiation and the amalgamation among the nations made the national culture more complex, inducing the national and religious conflicts which were of long history and hard to be resolved. It's the cultural fault zone, the intrinsic cultural origin of the national question why it existed for so long time in Yugoslavia.The second, B.J.Tito lead the Communist Party of Yugoslavia (CPY) reconstructing Yugoslavia into a united federalism state, with understanding the situation of Yugoslavia well, especially the national question. The national question in Yugoslavia became acute during the period of SFRY, the reason was that on the way of the reform of Yugoslavia autonoraic socialism, Federalism decentralized excessively, emphasized absolute equality of the nations, and this "confederalization" misplay of institutional leaded the national question in Yugoslavia to coming out again.The third, later in the 20th century, Yugoslavia had lost the especial strategic advantage in the Cold War. Moreover, with the impact from the upheaval of Soviet Union and East Europe, her system occurred profound transformation, together with politics and economy conjuncture, leading to the state abruption, which caused a series of conflict and threatened the safety and stabilization of the Balkan and Europe. In the same time, the great powers and international groups with their respective interests, intervened the situation in Yugoslavia, even became mediator to participator and leader. Thus, the national question in Yugoslavia in 1990s took on internationalization's character and trend, became the prism refracted the complex international relation and the world system after the Cold War.The basic structure and contents of the paper is as followed:Part 1 (two chapters): the national question in Yugoslavia before the middle of the 20th century.In chapter 1, the paper describe the geostrategic, national, religious, cultural and historical bases on which the national question in Yugoslavia is formed with regarding Yugoslavia as the convergent territory of the civilizations. It shows that the national question in Yugoslavia is complicated and exists long enough is greatly related to the fact that Yugoslavia lies in theconvergent territory of the Balkan civilizations. Yugoslavia lies in the southern part of European civilization' fault zone in which the Catholic civilization in West Europe, the Orthodox civilization of the Slav and the Islamic civilization of the Turk exist together. Several nation civilizations mingled and collided, which is the internal cultural root of the long existence of the national question in Yugoslavia.In chapter 2, the paper concerns about the nation-identity and nation-collision of several nations in Yugoslavia from the 16th century to the end of World War II. With the development of the west