Abstract: West Sichuan is one of the areas in China, where the debris flows occur centrally and its harmfulness is much more than that of any other areas. According to the analysis of this material, which is obtained by means of field study and laboratory study in the main roads of this area, we can know the mechanism of debris flow formation and its scale, intensity, type as well as characteristics. There are two debris flow ditches in the county town-Hanyuanxian-of this area. Having investigated, measured and calculated, in this material we put forward some plan of the road leaping over ditch and some idea of bringing a ditch under control.