Abstract: Dugushan landslide situated on the YK128+630m~YK129+050m of the Quan-San expressway. The landslide located in a concave area, where the upper of stratum is quaternary deposit and the lower is weathered residual stratum. Base on the existing terrain and landform, also the drilling core, the existence of ancient landslide is deduced in this paper. Collapse in top area of the Dagushan Tunnel is due to the engineering construction. Under the influence of rainfall and surface water in slide area, the ancient landslide which lie in the middle and lower part of the slope could be re-activated, and it can be ascribed to the weak permeability of bedrock. In order to guarantee the stability and safe of tunnel entrance and the Lin-pan-keng bridge, the Morgenstern-Price method is adopted for the calculation and analysis. Based on the result of calculation along a section of the slope, the landslide treatment is proposed. Anchored anti-slide piles have been arranged in the middle and lower parts of the landslide. In order to prevent the deformation of the bridge pier, anchored piles have been arranged in front of the bridge pier. Also the engineering counter measures to rainfall and surface water are adopted to stabilize the landslide.