The lower reaches of Jinsha River are the area that has the most serious problem of mountain hazards.Debris flow is one of the main mountain hazards in the area and it may cause damages to the construction and running safety of large hydropower projects.The evaluation method for the influences of debris flowon large hydropower projects was established firstly and then four ways（construction road,ancillary facilityand resettlement,sand in reservoir area and engineering facilities in the dam area）of the influences were elaborated.Heishui gully,lying in the reservoir area of Baihetan hydropower station,was taken as a typicalarea to evaluate the influences of debris flow on the hydropower project.Results indicate that debris flow ofHeishui gully may block the main river and thus its blocked backwater and outburst flood can cause damagesto construction roads and some temporary facilities.In addition,a large quantity of debris flow materials canflow into the reservoir and the storage capacity of Baihetan hydropower station decreases consequently.