Abstract: In this paper,it was shown that it would be underestimate the actual drought situation with the soil moisture method;and more and serious with the precipitation anomalous percentage,more and slight with the continuous clear day number might be obtained according to the service stipulated when we assessed the local drought situation.The author proposed one kind of improvement method in the regression synthesis equation with the classification of soil moisture and the precipitation anomalous percentage.It was close the actual drought situation.

Key words: Soil moisture, Drought, Classification