【Abstract】 The new mathematical model of the fuzzy comprehensive evaiua tion is used to the riskdegree of landslide and debris flow. Taking Zaotong Prefecture in Yunnan Province for example,the method and steps of evaluation are in troduced.In this way, 9 physical factors(such as relative altitude etc. ), which influence landslide anddebris fiow are chosen, and the factor set U is formed, The risk degree is divided into 5 clasqiliesfromhigh to low, and evaluation set V is formed.The basic evaluation unit is a county. The subordination degree of every factor in a unit isreplaccd by the probability, The fuzzy evaluation matrix R is formed by probability。 The set W of the weight iS formed with the de8ree of the incide nce betweeii factors and landslide and debrisflow, The evaluation re:uIts are obtaind with the of)erator(·,)and the evaluation formulaw。 R=and the maximum subordination principle. In this way,the risk degree of every coiintyof Zaotong Prefecture is obtained. 更多