Taking the landslide in AnKang reservoir as the research object,we adopt field investigation,laboratory test and numerical simulation to analyze the physical indexes and mechanical properties parameters of the rock under different water-dehydration cycles,and verify the rationality and safety of the supporting design. The effect of periodic fluctuation of reservoir water level on the reinforcement effect of anti-slide piles is studied. The main conclusions are as follows:(1) Under the water-dehydration cycle,the physical and mechanical properties of the strong weathering phyllite show the deterioration phenomenon,and there is a tendency to decrease slowly after the first rapid descent; (2) The stability of slope with the pile installed is improved greatly. With the increase of water level, the effect of anti-slide piles is weakened,and the speed is fast and then slow;(3) As water level cycles increases,the displacement and plastic strain bands gradually move to the trailing edge of the landslide,and the maximum force of the pile at the sliding zone is increased slowly.