During the past twenty years, political history has attracted less attention from historians of ancient China in Taiwan. This fact is usually attributed to the new developments of social and cultural history, which has become more popular in the historian community. Through reflecting on research of Song political history, however, this article tries to identify the reasons causing the decline of political history by an alternative method. Using Song political history as an example, this article argues that the failure to create new research subjects was the main obstacle for further developing political history. The fact that historians inclined to choose famous Song scholars as their research topic has produced many publications with similar subjects, and limited the possibility of managing research with originality. Moreover, without carefully analyzing the primary materials they used, some arguments lacked solid evidence. Thus, reviewing and reconsidering the subject and method of political history has become crucial for historians who intend to develop Song political history.