Abstract: Based on analyzing the characteristics of separating planes, structure of sliding rockmass and shear outlet, and compared with the Jiweishan landslide in Wulong, Chongqing, the formation mechanism of apparent dip slide in the Shanyang "8.12" landslide has been studied from five aspects, including steep stratified oblique rock, inclined stable rockmass barrier, free surface of apparent dip slip exiting, driving-rockmass sliding and relative stable rockmass resisting. According to the rapid long runout movement characteristics and the distribution characteristics of landslide mass, the motion process of this landslide can be divided into four zones, such as apparent dip shear slide zone, main slide accumulation zone, collision and retracing accumulation zone and fragment scattering zone.