Tao River water diversion is one of the most important projects of poverty alleviation and development in central Gansu during “The Tenth Five-Year Plan” period, with Jiudianxia water control project of Taohe River as the source of water, the water shortage in arid region in central Gansu is focused on. The administrative division of this project involves 6 counties of Zhuoni, Lintao, Weiyuan, Dingxi, Longxi and Yuzhong and the project includes 3 major landform units across mountain area of West Qinling, Longxi loess plateau and mountain area of Maxian mountain-Xinglong mountain. The geological condition is quite complicated with main geological hazards of collapse, landslide, debris flow and loess collapsibility. In this paper, the evaluation is carried out on debris flow, one of the main geological hazards, through lots of filed observation and in-situ investigation, and combined with the characteristics of linear engineering and debris flow distribution in this water supply project, the evaluation range is extended at both sides of the channel, the corresponding measures of hazard prevention and control are put forward.