Abstract: The intake slope of enlargement project of Fentan Hydropower Station is a thick-layered slope of good quality that dips backward.However,slightly toppling deformation occurred on the slope over the intake tunnels because of unsupported excavation of the slope and intake tunnels.This paper described the engineering geological conditions associated with the intake slope and analyzed stability of the thick-layered rock slope over the intake tunnels. The causes for slightly toppling due to excavation were analyzed and appropriate stabilization measures proposed.The field monitoring data show that the rock slope was stable after treatment.