College of Construction Engineering��Jilin University��Changchun 130026��China

In order to evaluate the danger of debris flow properly��eight factors were selected as the risk assessment indexes of the debris flow��namely the vertical slope��valley relative difference��hillside slope��area of basin�� loose solid material reserves��the path length of sediment supply probability��silting and scouring derricking and vegetation coverage�� The improved Analytic Hierarchy Process ( AHP) method was used to obtain the weights of the factors; and the efficacy coefficient method was adopted to evaluate the risks of six typical debris flow gullies�� According to the research��the improved AHP method not only avoids the subjectivity in the individual factor valuation by comparing two factors of each layer��but also makes the subsequent consistency check unnecessary��