Abstract: The safety boundary pillar is very important for safe production of underground mine which is transition from open-pit to underground mine,so it has to remain. Taken the Shirengou ore mine from open-pit to underground mining as an example，the safety boundary pillar at representative sections are calculated and analyzed by FLAC^2D, including deformation and failure of boundary pillar during caving. Meanwhile，the failure process of the different sections is simulated. By simulation, the safety and danger section of the boundary pillar is predicted. It also will provide scientific proof and guidence for the design of ore mine from open-pit to underground mining.

Key words: Transition from open-pit to underground mining, Safety boundary pillar, Numerical simulation