Abstract: Aiming at the end slope deformation and instability caused by end slope coal mining, this paper is based on the mining engineering practice of end slope coal mining of open-pit mine in Ordos area of China, a three-dimensional numerical analysis model for rock mass movement failure of the end-slope mining field which is under near-horizontal condition is established, the whole process of “coal seam mining-formation of mining cave group-failure of support coal pillars-instability of slope rock mass”, the characteristics of movement and failure of coal pillar and rock mass of slope are revealed, the key positions and trigger conditions of slope deformation and instability are proved. Based on the study of characteristic law, the bearing model of supporting coal pillars in end-slope mining field is constructed, based on the theory of sharp point mutation and safety factor evaluation method, a method to judge the stability of supporting coal pillars is proposed. The engineering application results show that this method can further improve the recovery rate of end slope pressed coal to more than 60% on the premise of ensuring slope stability.