Risk assessment of geological hazard is the study of damage degree of human life and property affected by the geological disaster. It is of great importance for reducing harm level of geological hazard fatalness, preventing and controlling of geological disaster. As an example in Wudu area of Longnan City, we choose topography, lithology, meteorology, hydrology and human activity as the hazard assessment factors, on the basis of detailed investigation of geological conditions in study area. Then, adding the importance of the residents activity area as a risk assessment factor, we have finished the geological hazard assessment and its risk assessment by GIS combined with AHP. The result shows that the proportions of geological hazard risk of non-risk, low-risk, medium-risk and high-risk area are respectively 31%, 14%, 25% and 30%.