Abstract: The advancement of comprehensive drought resistant index of crops and its limitation on application were explicated .Surveying from the yield in index of evaluating the drought resistance of crops at present, Principle which we regard as equally important in line with the yield and quality of crops ,comprehensive drought resistant index of crops were put forward, the expression formula of mathematics is as follows: CDI =(DC or DI *100+I) /2. Controlling water treatments (CWT) for the two varieties, Shangyu 397 and Suijing 3 of different soil water potential were carried out during different periods, comprehensive drought resistant index of panicle formation stage was the smallest. Therefore , water sensitive stage of yield and quality was panicle formation stage.