Abstract: In order to analyze direction of maximum principal stress on stability of surrounding rock, plastic zone, deviatoric stress and displacement during angle from 0°~90° are simulated by Flac3D. It is concluded that plastic zone area of “surrounding rock” is larger with the increase of α, and develop to depth of roof and floor. Deviatoric stress is a “single peak”, and peak of deviatoric stress of roof and floor increase with increase of α, but sides are opposite. Displacement also increases “linearly”, and direction of maximum horizontal stress on deformation of roof and floor surrounding rock are greater than that of the sides. The reliability of analysis results is verified by field observation.