Abstract: In order to further study the deformation evolution mechanism and failure mode of slope under lateral orthogonal mining disturbance, based on the background of mining disturbance slope in mountainous area, combined with field investigation, FLAC^3D numerical simulation software was used to construct a three-dimensional geological model of mining slope, and the variation law of stress field and displacement field of slope at different advancing positions of working face was analyzed. Combined with the analysis of GNSS monitoring data, three deformation evolution stages and failure modes of the disturbed slope of lateral orthogonal mining are proposed. The results show that under the disturbance of lateral orthogonal mining, the concentrated stress of the free surface of the slope is gradually released, the deformation disturbance of the surface is generated before the lower rock mass, and the non-uniform shear deformation along the slope direction is generated at the top of the slope, and the non-continuous failure occurs. When the horizontal distance between the working face and the slope is 50-55 m, the deformation amount mutates, the rock mass at the upper edge of the slope deforms plastically, and the tensile cracks extending intermittently along the slope trend appear on the top of the slope, which weakens the range of the surface affected by mining disturbance. When the working face passes through the slope section and the horizontal distance between the two is beyond 120-170 m, it enters the stage of deformation recession and the deformation rate slows down. At this time, the deformation increment of the slope in the vertical direction is greater than the horizontal deformation increment. The overlying rock mass of the crack produces the extrusion effect pointing to the free surface, and the crack gradually closes; the slope generally presents a non-uniform shear-cracking-closing deformation and failure mode.