History textbooks are oftentimes utilized as tools for conveying and shaping nationalism. Such textbooks have gone through changes in content to reflect evolving views of nationalism in accordance with the development of history and shifts of social purposes. While a majority of current literature focuses on nationalism in history textbooks, few pay attention to the long-term continuity and shifts of discourses on imagined nation over the past century. Based on Benedict Anderson’s (1993) notions of nationalism as an imagined community, this research attempts to investigate how nationalism has developed and changed in high school history textbooks of the past century. It also aims to reveal how textbooks served as a political and social tool in promoting and substantiating particular kinds of nationalism by, for example, making distinctions between national identity and the other. Using textual analysis, we scrutinize texts, stories, pictures, discourses, and the ways in which they are selected, narrated and organized in history textbooks to fulfill our research aims. Textbooks used in this study will be from collections housed by libraries in Taipei, Shanghai, and Beijing. The research manifests its significance in two ways. First, by analyzing and comparing nationalisms in history textbooks from different time periods, the research provides a comprehensive understanding of different notions of nationalism. Second, this research lays down a theoretical and empirical foundation for reconstructing discourses on imagined nation in history textbooks.