The meteorological information,such as precipitation and thermo hydric status in atmosphere,could be easily obtained at any time. How to use these data to report the seasonal drought change,for example,based on the characteristic of rainfall: seasonal and effective precipitation,the hysteresis of soil layer moisture and according to the thermo hydric status in the atmosphere,the drought index was developed. The drought seasonal monitoring and forecast and the measurement of the drought disater degree was also studied simultaneously.