Abstract: Weak structure face is the key point of rock slope stability. In particular, the anti-dip weak structure face at back edge of the slope can control the stability of that slope. Such problem is complex because the stress applied to the face at the back edge sometimes is not clear. This paper presents a numerical analysis of such a rock slope problem. It is to assess the stability of a rock slope inside the approach channel of Jingping Hydroelectric Power Station. The factor of safety of the rock slope is found to be 1.191. The rearward rock mass is found to have no stress to the front slide block. Both the numerical method and the limit equilibrium method were used to discuss the parametric sensitivity of the weak structure face. The results of the two methods show that the numerical method with strength reduction is suitable to assess the stability of this rock slope.