Abstract: According to the dam safety appraisal, the initial design of reinforcement and construction , as well as the investigation at site, deformation monitoring, exploration testing information etc. after the landslide of the upstream slope happening, in combination with the slope stability analysis, the landslide causes of the upstream slope of the main dam were analyzed, and two treatment programs, i.e., one was the landslide body to be removed and refilled, and the other was the damaxis to be moved backward, were recommended to deal with the landslide. The former was adopted. The dam is running at present, and in perfect order.