Abstract: In order to study the influence of valley slope on mining-induced sliding type fracture development law during loess gully region mining, based on mine mining geological conditions, we use numerical simulation software UDEC to analyze and study the relationship between crack distance, crack angle of sliding type crack and slope under different valley slope, and get the crack distance, crack angle of sliding type crack under different conditions of valley slope. The results show that crack angle and crack distance of slide-type crack and valley slope presents a quadratic polynomial relation during mining in loess gully region; with the increase of valley slope, the crack distance increases first and then decreases, the crack angle decreases first and then increases; valley slope is obtained when crack distance, crack angle of sliding type crack reach extreme value; sliding type ground fissures in coal mine will cause certain harm for coal mine safety and ecology, we propose some measures for this problem.