The famous prescription ,Wuling, Powder recorded on ,Treatise on Febrile Diseases, was written to treat Taiyang water retention by ZHAGN Zhongjing. It has the function of clearing damp and promoting diuresis, strengthening spleen and invigorating Yang. Professor ZHANG jingsheng, the first national famous Traditional Chinese medicine physician, is good at using ,Wuling Pow-,der to treat various internal and surgical diseases. In this article, the source of the classical theory of Wuling Powder was excavated, 11 provisions on ,Wuling, Powder recorded from ,Treatise on Febrile Diseases and Synopsis of the Golden Chamber, were thoroughly combed, 6 provisions of which were elaborated, and the emphasis is placed on ZHANG's unique understanding of the provisions. Then combined with the application of ZHANG's in a variety of specific diseases, it points out that ,Wuling, Powder is not only used in Taiyang water retention and phlegmatic cholera recorded in the classics, but also widely used in treating various kinds of diseases, such as spontaneous sweating, diarrhea, urinary tract syndrome, diabetes insipidus, polyuria enuresis, testicular hydrocele, idiopathic edema of Meniere's syndrome, cardiogenic edema. The treatment interpretations of the diseases, combined years of clinical experience, dosage using and compatibility regularity from Professor ZHANG jingsheng, can be used in the clinic. It also can play the role of enlightenment on flexible using of the classic and expanding the scope of application on classic prescriptions.