In this paper ,a soil moisture simulating model is used to provide necessary infomation for ana-lyzing regional drought. The long- term average daily soil moisture are used as drought determinants.After statis-tical analysis,a method for analyzing severeness of regional drought,specially for plain area,has been given whilea quantitative criterion of drought has been set up the method has been put into test utilization for the HuabeiPlain. The results show a coincidence with the historic records,The method proves practical and prospective