Abstract: The rock slope will take place large deformation,damage and stability issues during the transition from Yanqianshan open-pit to underground mining.The mine excavation characteristics in different depth was analyzed with FLAC large deformation mode.The soft rock mass in North slope collapse easily and heavily.But the sliding is not rapid usually,and has a less influence to underground mining.But large number of small crushed stones will fill the rock layer,which is unfavorable to control the dilution and loss index.The hard rock mass in south slope have not appeared large deformation and sliding during primary mining.

Key words: Large deformation mode, FLAC numerical simulation, Transition from open pit to underground mining, Slope stability