Based on the growth features,this paper discusses the efficacy characteristics of Mahuang(Ephedrae Herba)and its application in edema diseases. It grows in a dry and cold land,with no snow in winter. The medicinal parts are hollow and straight up and down. The efficacy characteristics can be summed up as “expelling” and “dredging”. The “expelling” means sweating,inducing diuresis and relaxing bowels,the “dredging” refers to promoting blood circulation for eliminating abdominal mass,warming and regulating yang qi. Mahuang(Ephedrae Herba)can regulate the internal organs function,such as lung,kidney,bladder and Sanjiao,which are closely related to water-fluid metabolism.