The Chinese nation has accumulated rich resources of thought on national security throughout its history. Among these, Chen Liang, a representative figure of the “Yongkang School” in the Southern Song Dynasty, proposed a series of substantive ideas on national security based on his profound insight into the crises of his era. His theory of governance, encapsulated in the maxim “establish the fundamental principles to rectify discipline, and define the grand strategy to enable adaptive actions,” was founded on an understanding of the systematic security crises in the early Southern Song, emphasizing the foundational role of core principles and overarching strategy. His view of rule of law, expressed as “acting with utmost impartiality in accordance with the times,” originated from reflection on and critique of the limitations of the Song Dynasty’s legal institutions, embodying the requirement to unify principled rigor with flexibility. His practical character, centered on the idea that “Tao is manifested in Shi (concrete affairs)”, was fully demonstrated in his famous debate with Zhu Xi on “The Kingly Way” versus “The Hegemonic Way” and Yi (Righteousness) versus Li (Utility), which were reflected in his ontology of “the unity of Tao and Shi”, his methodology advocating for “the concurrent practice of Yi and Li and the integrated application of the Kingly Way and the Hegemonic Way,” and his subjectivity characterized by “responsibility and broad-mindedness.” Chen Liang’s thought on national security, underpinned by his “Practical Statecraft” provides profound historical and cultural support for constructing an autonomous knowledge system of Chinese national security studies.