Abstract: As a kind of representative landslide, accumulative stratum landslides in horizontal stratum have special forming causes and deforming-destructing characteristics. This paper studies the accumulative stratum landslide in Wanzhou and then analyzes the characteristics of the accumulative stratum landslide, sources of matter, causes, forming mode and deforming-destructing characteristics of the accumulative stratum landslide in horizontal stratum. The characteristics of landslide body and bed are then summarized. Falling accumulation is primary and diluvium and alluvium are subordinate to the accumulative stratum landslides in horizontal stratum. The forming mode have six steps: a) cliffy forming, b) landslide bed forming, c) bottom matter of landslide body forming, d) soil and stone forming and, e) the surface matter forming and disaggregating. The deforming-destructing characteristics are as follows: several shear zones can exist in the accumulative stratum landslides. At the same time, deforming velocity and accumulating deformation in different areas are various in the accumulative stratum landslides.