The Bailu ditch located in the transitional area between Chengdu plain and West Sichuan Plateau.It has a large catchment area，the most slope of gully are steep.Based on the investigation of geology，geomorphology，hydrogeology，climate and human activities，the formation conditions，characteristics of erosion and deposition of debris flow are analyzed，and the development trend of debris flow is studied.According to the characteristics of study area such as the rich source，long time rainfall or concentrated rainstorm in the study area.Bailu ditch is assessed as a mega and movable debris flow.Once the outbreak of debris flow，it will pose a serious threat to the safety of nearby residents，buildings and the normal operation of the project.This paper provides a scientific basis for the comprehensive management of the basin.