In order to grasp the seismic response characteristics and damage states of anti-slide piles in service in the strong earthquake area of southwest China, a three-dimensional finite difference model of anti-slide pile reinforced rubble soil slope under different damage states was constructed based on a typical site located in the strong earthquake area of Sichuan-Qing railway. The acceleration response of slope, the change of internal force of anti-slide pile structure and the influence of initial damage of pile body on the dynamic response of slope were studied. The wavelet packet energy spectrum method was introduced, and based on the acceleration response data of pile body, the energy damage discrimination index was constructed to identify the damage state, damage location and damage degree of pile body. The results show that the anti-slide pile can effectively reduce the acceleration response of the soil around the pile body, and the acceleration of the slope body generally presents an elevation amplification effect. The loading area near the sliding surface of the pile body is concentrated, and the damage of the pile body will lead to the decline of its flexural and shear bearing capacity and the increase of lateral horizontal displacement, which will further aggravate the acceleration response of the slope body. The distribution characteristics of damage discrimination index D_PERV along the pile body can effectively identify the damage location and damage degree of anti-slide pile. The established quantitative relationship among pile top residual displacement, pile top damage index D_PERV and damage degree can evaluate the relative damage degree of pile body, providing a new idea and method for evaluating the service performance of anti-slide pile in slope engineering.