Lishan slope, constituting an important part of the Huaqing Palace, is subjected to obvious deformation. The monitoring system set up by the Disaster Prevention Research Institute, Kyoto University (DPRI), headed by Professor K. Sassa, has revealed the instability of Lishan slope. On the basis of the monitored data, the author of this paper conducted a series of computation of the slope stability under different conditions by using FLAC program. The results obtained show that the Lishan slope is an unstable one and it is hard to resist the triggering force of ground motion due to strong shock and the influence of intense rainfall. The risk of slope stability should be prevented by slope reinforcement.