Abstract: Huge high-steep unstable rock mass is more prone to failure of fracturing-crashing at the bottom due to self-difference under the combined action of multiple factors such as dead weight load and human engineering activities. The rate of damage and deterioration of the bottom zone is faster, which becomes the weak link affecting the overall stability of the unstable rock mass.The mechanical difference of such huge rock mass is often neglected in the conventional stability analysis. Based on the damage theory, a method for assessment the stability of high-steep unstable rock mass is proposed, which takes into account the difference of rock mass and damage. The Jianchuandong unstable rockmass was taken as an example, and the comparison between the standard method and the method proposed in this paper shows that the method considering the damage zone is more consistent with the actual situation.Our study also indicates that when the height H of high-steep unstable rock mass is determined, the smaller the weak zone at the bottom (that is, the greater the ratio of H/h), the greater its overlying load is. The influence on overlying load is obviously weakened when the ratio of H/h is more than 10. The growth ratio of overlying load is only related to the ratio of H/h, and it doesn’t change with H. When the ratio of H/h is constant, the growth rate of overlying load of the weak zone at the bottom is linearly correlated with H. This research can provide a new analytical method and reference for geohazard prevention and reduction of huge rock collapses in southwestern mountain areas of China.