The terrain and topographical characteristics loosening solid matter characteristics and rainfall characteristics as well as statics and dynamic characteristics of giant debris flow were obtained by field investigation and analysis on the debris flow hydrodynamic force conditions based on platform of ArcGIS and using DEM. The results show that the terrain and topographical can provide favorable condition for formation and running of runoff. The amount of loosening solid matter is so great that amplify dam. The severe local weather process with heavy precipitation short duration is the main cause for this massive mudslide. The great destructive of debris flow in circulation terrain is mainly down cutting erosion, affected by the terrain, the impact force is decreased and the debris flow stacked.