Based on meteorological data from 11 weather stations during 1970-2000 and data of soil moisture from 5 agro-meteorological observation stations during 1981-2000, the frequency of heavy rain and storm and the variations of soil water content and potential soil water content were analyzed. The index used to as-sess possibility of debris flow had been created. Results showed that under heavy rain, the possibility of deb-ris flow in Xihan River valley is greater than that in Bailong River valley, while under rainstorm, the possi-bility of debris in Bailong River valley is greater than that in Xihan River valley.