Abstract: On the basis of 16 independent variables (including 8 remote sensing factors, 3 DEM factors, 4 soil factors and 1 formation lithology factor), the intraday precipitation rainfall and that in preceding day were extracted as the dependent variable respectively, and the random forest regression tree model was built to predict the debris flows in the regional scale on the platform of GIS. The predicting results shows that, the lithology, elevation and aspect are the main factors influencing the occurrence of debris flow, and the increasing precipitation improved the importance of the soil factors in the occurrence of debris flow. Among the 8 remote sensing factors, the clay factor has the greatest impact on the debris flow. In the southeast, the debris flow would occur when the accumulated precipitation goes higher. On the contrary, in the northwest, a small amount of accumulated precipitation would result in the occurrence of debris flow, and the continuous precipitation would increase the incidence of debris flow from the daily and two day precipitation warning charts.