The Theory of Fire-Heat, first established by Liu Wansu in the Jin Dynasty, remains a fundamental idea in Traditional Chinese Medicine (TCM). It teaches that excessive internal fire and emotional imbalance are important causes of disease. Although this theory has guided clinical work for centuries, its relevance and application in modern medicine deserve new interpretation. This paper reviews the historical origins, theoretical foundations, and clinical applications of the Theory of Fire-Heat, as well as its value for future development. Based on literature review, analysis of clinical cases from several TCM hospitals, and expert interviews with experienced clinicians, the study explores how Liu Wansu’s ideas continue to guide modern treatments for metabolic, cardiovascular, skin, and emotional disorders. The discussion also connects these traditional concepts with biological mechanisms such as inflammation and oxidative stress and considers how technologies like artificial intelligence and big data can support future studies. By combining classical wisdom with evidence-based medical thinking, this paper provides a practical perspective for the modernization and internationalization of TCM.