Abstract: Concrete production system of Gushan hydropower station is located in an old landslide. Excavation induced serious deformation in the old landslide, which severely damaged the engineering construction. Through the systematic research on engineering geological conditions and deformation characteristics of engineering site, the deformation was mainly caused by improper construction excavation, rainfall and groundwater activity. Other factors also played a certain role in triggering. The excavation had dismembered landslide into three parts:the east, the middle and the west. The landslide deformation has a great influence on the overall stability to the west, but little to the east and middle areas. Emergency engineering measure has been adopted to deal with the landslide deformation characteristics. According to excavation status and stability condition, this paper assesses the stability of the landslide under different situations. The results show that in the natural state, besides the east ② regional landslide deformation in an unstable state, the west in a less state, the other parts are in the basic stability to the steady state. Under the condition of continuous heavy rainfall, the whole landslide is in a less stable or unstable state and needs to be governed.