Abstract: Liangshuijing landslide appeared dangerous condition during the first 175m experimental water storage in the Three Gorges Reservoir area, which attracted widespread attention of many geological disasters related departments and the community. On the basis of exploration, through the analysis of topography, geomorphology, material composition and geological structure, and combined with numerical simulation, the formation and reactivation mechanism of landslide is analyzed. Research show the following results,(1)Liangshuijing landslide is an old landslide formed by twice slip. It is an progressive landslide affected by the water soaking and water level changes, which induced by upper sliding body deformation dislocation in the running process of the Three Gorges Reservoir area.(2) At different stages of reservoir operation in the Three Gorges Reservoir area, the whole stability of landslide is reduced by influencing the different parts of the sliding zone.(3)Due to the thickness of the front slide body is large and lower block size is huge, contacts are formed between stone and slide bed. The sliding surface is easy to form a pillar role and locking effect in the middle relatively slow section, which make the landslide not instability.