Abstract: Risk analysis of landslide is one of the critical factors for the selection of dam site. Through field investigation and data analysis of Tiansan landslide in Kala hydropower station, risk analysis model is established. With Bayes statistical methods and Monte Carlo method to determine the parameters, considering the combination of rainstorm state, water-storage conditions, earthquake and other conditions, the analysis of stability, surge and river blockage of Tiansan landslide are done. Risk analysis of Tiansan landslide provides experience for failure mechanism in the region, which will facilitate the determining of the dam site selection.