Xuan Fu (sweat pore) theory was derived from Huangdi Nei Jing (Canon of Internal Medicine), formulated by Liu Wan-su in his Su Wen Xuan Ji Yuan Bing Shi (Pattern of Mysterious Mechanism of Pathogenesis in Plain Questions) in the Jin Dynasty, and perfected by doctors later. The article introduces the establishment and development of Xuan Fu (sweat pore) theory from its concept and function, pathology for its stasis, therapeutical principles and treatment for opening Xuan Fu, its special theory and modern exploration in its essence.