Accoding to the debris flow development history, geological, geo-morphical and precipitation conditions,this experiment initially analysesthe distribution, cause and developing tendency of debris flows in Xihecounty. It is considered that the debris flows of this county distributesalong with structural beld with the changes of rock character and artificial destruction of vegetatin. Relying on these,the authors deduce the cau-ses of debris flows and discuss the forming of debris flows with relation totopography, the storage of solid materials, water supplies and new tectonicmovement. It at last draw the conclusion that the debris flows tend ofthis county will come into an expanding stage and become serious soon.