Abstract: "Heart governing the exterior" is a representative theory of the "integration of viewpoints" feature in The Inner Classic, with rich theoretical implications and extensions. Considering the structural characteristics of the heart's visceral orifices and numerous somatic orifices in the superficial body, the physiological characteristics of the heart's yang symbolizing fire and the physiological characteristic of heart yang being analogous to fire, which is characterized by flaring upward and diffusing outward, as well as the functional characteristics of the heart governing blood circulation, spirit, and the ability to control all things, combined with the interpretations of successive commentators on The Inner Classic, it is believed that the "exterior" is the distribution area where the heart reaches the essence, qi, and spirit, the area where the heart governs the functions of the body, and the area where the heart governs the signs of life activities. The theoretical extension of "exterior" not only refers to macroscopic tissues and organs such as the skin and the nine orifices, but also covers the microscopic pore/gap structure of organs and orifices such as the area between the muscles, acupoints, sweat pores, Xigu, and Xuanweifu. The clinical application scope of "heart governing the exterior" is relatively broad, mainly focusing on cardiovascular, skin, external infection, five senses, mental and neurological diseases of heart exterior disease. Only by solidifying the understanding of the theoretical connotation of "heart governing the exterior" and expanding the scope of its extension can we promote the clinical application and transformation of this theory and improve the clinical efficacy of heart exterior diseases.