Abstract: Affected by Qinghai-Tibet Plateau rapid uplifted and the river fast incised in Western Sichuan plateau since Cenozoic, where develop more and more bank slope and steep cliff that have the characters of high and steep、complex slope type、 and broken rock. Hongjunshan Dangerous-rock Slumping has the characters of large-scale、wide distribution、diversity failure pattern and complex mechanics. On the basis of engineering geological mapping, this paper investigates the distribution of dangerous rock, size, damage characteristics, failure mode, studies for different modes and stability calculates of the dangerous-rocks. Main knowledge:(1) the rock mass structure has obvious regional and zonality.(2) the generation and dangerous rock destruction are mainly block instability, ladder shaped sliding.(3) stability of dangerous-rocks are calculated for considering natural, rainstorm, earthquake conditions according to the characteristics of development、mass deformation and failure mechanics. Biggest dangerous rock mass, the lung deaf dangerous-rock, is stability under natural conditions. But is primary stability to instability under conditions of heavy rains and earthquake. Others are mainly instability under three conditions.(4) We suggest that some prevention measures should be taken, such as remove reinforcement, monitoring and the rainy season cruise screening for dangerous-rocks.