For the study of East African history and Pan-Africanism ideology，the coalition of Tanganyika and Zanzibar is a fundamental issue in academia，which focuses on the reasons，motives，and impacts of the union. Domestic and international academia’s views on the Tanganyika-Zanzibar union are discussed around two major models，namely “Cold War politics” and “Pan-Africanism ideology”，yet both perspectives infer the causes from the results and fail to explain the uniqueness of Tanzania as the only special case of a union between two independent sovereign states that has continued in Africa to this day. Additionally，they lack a deep understanding of the political leaders’ motivations on both sides of Tanzania. The author believes that although the political leaders on both sides of Tanzania had different political goals for the union，the union not only met the political demands of both sides but also demonstrated a high degree of integration between African nationalism and Pan-Africanism in the context of the Cold War. Behind this，it revealed a turning point in African political thought during this period.