Abstract: In view of the different undercut means in the block caving mining process of Pacific Mining Company,the PFC2D software is used for comparative simulation and analysis.By simulating the stress change law corresponding to different undercut advance distance,it is finally determined that the optimal undercut means is forward undercut for Pacific Mining Company,and the undercut advance distance is 25-30 m.Within the distance,the pressure on the bottom structure and ore-drawing engineering is relatively small,and the overall stability of the bottom structure is good,which is conducive to lowering support cost.The means can provide theoretical guidance for the nextstep safe and efficient mining in mines.