The rotational-translational landslides are accumulated in the northeast margin of Tibet Plateau. To analyze the dynamic mechanism of nearly horizontal sliding band transformation, this paper described the distribution features and geometric strain model of rotational-translational landslide based on outdoor survey, experiment and numerical simulation calculation. Some conclusions have been reached: (1) the rotational-translational landslides were concentrated in the Pliocene mudstone basin on the northeast margin of Tibet Plateau. The activity intensity of these landslides are affected by the uplift process of Tibet Plateau. Its volume gradually recedes from the hinterland of the Plateau to the marginal basin. The giant landslides concentrate in the upstream area of the Yellow River system, while the large ones distributed respectively in the downstream areas; (2)The slide mass of rotational-translational landslide are all composed of Pliocene mudstones with high clay contents and over-consolidation features. The nearly horizontal shear stress in slide mass was controlled by water flow erosion. Under the effect of this stress, over-consolidated mudstones tend to swell and show dilatancy and progressive damage. The thin shear zone present ductile and brittle deformation; randomly arrayed clay particles in the area gradually fix their positions and show up as internal friction angle below 10o , and (3) the sliding surface select the weak layer with high clay content and low calcium content for extension by the deformation of creep and crack. This process had been accelerated as the content of pore water and the rheology of sliding zone increased. So the macro movement of sliding mass was determined by creep and glutinous flow of clay minerals in the sliding zone, which is one of the driving factor of landslip deformation.