Abstract: To satisfy the increasingly urgent demand for prediction of natural disasters, risk assessment is one of the fundamental tools for helping the decision-making process. Even though individual components of debris flow risk are difficult to be accessed, the availability of geographic information systems helps in proposing pertinent methods for the mapping of such risk. This paper describes the systematic methodology used to establish a GIS capable of identifying and quantitatively rating areas of debris flow risk. In this study we elected 6 causal factors from the initial set for susceptibility analysis of hazardous degree in Yuannan Province as study area. By overlaying vulnerability map of the study area to hazard map, debris flow risk map was created, which depicts relative risk susceptibility of areas to debris flows under existing natural conditions and human activities. The proposed method for debris flow risk assessment by geomorphologists is one of the most important methods to show hazardous situation, assure objectives of disaster-reduction, optimize prevention and control measures.