Abstract: In recent years,there has been numerous outbreaks of lage-scale debris flow disaster in Nujiang Prefecture of Yunnan Province,which have caused heavy causalties and property losses.This paper takes debris flow of Lanping County,which boasts of rich mineral resources and hydropower,as the research object.By Site survey,combined with the existing research achievements,it scrutinizes the spatial distribution of debris flows in Lanping. After that,it builds hazard assessment index system of single debris flow based on key driving force,which consists of geographical,hydrodynamic and gravitational dimentions,using AHP and GIS technology to carry out risk evaluation.The research finds that among the 79 debris flows in the study area,there are 31 gullies at high risk and 32 in medium risk.Besides,The right and left banks of Lancang River are respectively concentrated with high and medium risk of debris flow gullies.Also,furthur analysis indicates that precipitation influences the occurrence of debris flow in Lanping.From the right bank of Lancang River to the left side and to Tongdian river,precipitation gradually decreases,so the risk of debris flows is reduced gradually at the same time.The findings of the research may be helpful to guide the construction of large-scale projects and secure its operation in Lanping County.