Abstract:The typical slope failure examples above mine-out area was took as the research object in Guizhou province and the finite difference software FLAC_3D was used to analysis evolution law of the vertical slope stress, horizontal displacement and shear strain increment at different time steps, while deformation and failure mechanism of slope is also discussed under this mode. Analysis result shows that: the toe of slope was compressive stress concentration zone, the peak of which up to 4MPa, while the position of which prone to compression shear deformation, the top of slope was in tensile stress zone; the horizontal displacement of peak area was distributed mainly on the top and toe of slope as a result of upper-hard-and-lower-soft structure; the region of soft rock and the clay in slope was easily produced plastic deformation, while hard rock can temporarily hinder the plastic zone flowing ,however, slope eventually form a continuous plastic zone, resulting a perforation between slope cracks and goaf .