Abstract: The settlements in tibet hydropower station has a lot unstable rocks, poor stability~very poor stability, risk of large may collapse, and have a serious threat to people and property in settlements and the highway traffic safety. In this paper, have an evaluation and grading on the risk of unstable rock, by using the Highway Public Corporation Law of Japan and the ROCKFALL software, analysis the falling distance, jumping height, the total kinetic energy, horizontal movement distance of the unstable rock, and obtain the relationship between the movement of unstable rock and the settlements, finally, give a reasonable prevention recommendations and a scientific basis.