Abstract：According to the structure characteristics of the joint rock mass of the south slope of Yanqianshan Open Iron Mine，the 3D joint network is simulated and shown by Monte-Carlo random simulation technique based on the joint surveys in-situ and statistic analysis；and the strength of the jointed rock mass and the failure modes of the slope have been defined. The stability states are systematically studied by means of searching automatically the critical slip surface and FLAC numerical simulation for the present executing project and the revising project. That the slope angle of three benches becoming one large bench is revised from 65° to 60° can basically improve the stability state of the south slope；and meet the mining stability demand during the service life of the open mine.
