This paper introduces the clinical experience of Professor Li Samei in applying Mahuang Shengma Decoction. Combined with the original text of the Shanghanlun(Treatise on Cold Pathogenic Diseases)and the annotations of ancient and modern doctors, this paper discusses the recipe, and syndromes, etiologies and pathogenesis of the diseases treated with Mahuang Shengma Decoction from the aspect of correspondence between prescription and syndromes. Mahuang Shengma Decoction has the functions of dispersing stagnant yang, clearing away heat of the upper and warming yang of the lower part of the body and harmonizing cold and heat, which is used for the treatment of the spleen yang damage due to incorrect treatment of exterior syndrome by purgation, stagnation of heat in the lung and stomach,invasion of Jueyin by pathogen, and interior stagnation of yang qi. One proven case is presented .