This thesis starts from Anderson¡¦s theory of ¡§Imagined Community¡¨, through the angle of ¡§Nationalism¡¨ and the ¡§Historical State Approach¡¨, to study the development of ethnic politics in Indonesia. In the analysis of historic events, this research hopes to represent the phenomenon of ethnic politics in Indonesia. According to the development of Indonesian Nationalism, this dissertation divides the political history in Indonesia into four stages, ¡§the independent stage¡¨, ¡§the national integration stage¡¨, ¡§the national cooperation stage¡§ and ¡§the democratic transformation stage¡¨, also there are two factors----¡§the state dominate¡¨ and ¡§the ethnic group politic mobilization¡¨ ---- being cross-compared their relations within the four historic stages. This thesis concludes: Indonesia as an ¡§imagined community¡¨, which leads the cleavage in the Indonesian national society. Lack of efficient institution for national integration at the beginning of the national independence, the cooperation politics in the New Order stage, both tended to build the inequality between different ethnic groups, which is the main reason for racial conflict after the democratization, and also the general factor affecting the ethnic politics in Indonesia. Individual factors affecting the ethnic politics in Indonesia include elements of the culture in religion, of the economy in region and the history in international politics, of the racial immigration and economy¡Kwhich form the ethnic consciousness and ethnic identity. Under the effects of the general and individual levels, nowadays the Indonesian ethnic politics presents itself as¡GA. Religion: Muslim parties contestation, the religious demonstration outside the institution, and the regional conflicts in religion. B. Region: secessionism, islanders demanding for regional autonomy or for federalism. C. Race: race violence against Indonesian Chinese, regional racial murders caused by the interior immigration policy. This dissertation concludes with elements of the above three levels, which show the phenomenon of contemporary ethnic politics in Indonesia.