Abstract: Based on historical and realistic data,debris flow hazard of 18 cities in Henan province were researched using AHP.As a new criterion,city-importance was introduced in evaluation system of AHP.Henan province was divided into five intervals based on hazard degree weights of debris flow.Among 18 cities,one city belongs to large-hazard-area,3 cities belong to medium-hazard-area,6 cities belong to small-hazard-area,2 cities belong to minimum-hazard-area,and 6 cities belong to no-hazard-area.Moreover,a formula was got to forecast the occurrence of debris flow in Henan.