Based on the Nierwan landslide in the Three Gorges Reservoir Area

through the establishment of the seepage and stability analysis model

the effect of the water level rise on the stability is studied;and the 3DEC discrete element software is adopted to establish the two-dimensional discrete element motion model of the landslide and deeply analyse the movement pattern and deformation law of destruction.The results show that

（1）from the point of instability mechanism

reservoir filling is one of the important factors inducing the landslide instability;（2）from the perspective of the motion law after the destruction

the horizontal displacement in the space from the landslide trailing edge to leading edge and from the surface to the deep is gradually increasing.Its growth rule in vertical depth conforms to the Logistic growth model

and in hyperbolic type growth on time;vertical displacement in the space from the landslide trailing edge to leading edge in turn reduces

and changes little along with the sliding body vertical depth.（3）The landslide deformation and failure mode can be divided into translation and rotation mode.