The stability of the talus slope is important to its construction and operation. We draw a conclusion on site that it is a incised gully collapsing talus slope that are consisted of bedrock and unconsolidated deposit. There are evidence close up and turn around between the elevations of 1 360－1 450 m

the elevations of elevation which are contributed to its stability. The data that by using 3D numerical simulation (3D-Sigma and 3D-Flac) show that ⑴Stress field of the talus slope is main weight field

its stresses distributes is mainly controlled by lithology; ⑵ Latent sliding surface is the interface of talus and the bedrock and above it in some height. ⑶ The displacement is toward to limit surface; and the displacement of the middle-front part of the talus slope is large; ⑷ The front zone’s close up improves stress state and raises the stability of talus slope; ⑸ It is wholly stable

but it maybe occurs middle-superficial layer failure between the elevations of 1 472－1 610 m .