During the operation of outlet high slop of the hydropower station diversion tunnel, the monitoring data shown that the upper slope had an abnormal deformation tendency toward the upstream, which was different from the general slope deformation law. The paper analyzed the deformation mechanism of the high slop outside the hydropower station diversion tunnel in detail based on detailed analysis of the geological data. The analysis shown that the basic reasons of slope deformation were the upper hard and lower soft structure characteristics and the fully developed interlayer shear zone; the excavation unloading, reservoir impounding, reservoir water level change, rainfall, flood discharge atomization, rock weathering, water-rock long-term effects, and some other factors induce and aggravate the rock mass deformation.
