The terrain and geological conditions in the mountainous area of western Sichuan are complex and changeable. Dangerous rocks are mostly developed in high and steep slope sections, which pose a serious threat to the safety of highway traffic after collapse. Taking the tail perilous rock of Qiaoqi Reservoir in Baoxing County of Ya 'an City as an example, the basic characteristics of perilous rock were analyzed by means of UAV aerial survey and field investigation. Rocpro3 D software was used to simulate the three-dimensional kinematics to evaluate the collapse damage. The results show that the formation of dangerous rock in the working area is caused by the combined action of tectonic compression, rainfall erosion and weathering unloading. Strong rainfall and strong earthquake are the typical causes of dangerous rock collapse. The maximum impact energy after the collapse of dangerous rock in the working area is more than 5000 kJ, and the removal of large-size dangerous rock can effectively reduce the impact energy value. After the collapse of the dangerous rock in the working area, it shows the stage motion characteristics of rolling along the slope → bouncing after hitting the road surface near the surface of the 351 national highway → stopping the accumulation of the riverbed and bank slope of the East River. The treatment scheme of dangerous rock removal + passive protection network + open hole + frame anchor rod can be used for prevention and control.