Abstract: Taking a special mining engineering in Inner Mongolia as background, aiming at the shallow occurrence of coal seam and the stacking dump of earth surface and other special circumstances, we use unprotected coal pillar from open-pit into underground mining scheme. With the principle of production efficiency and avoiding the disaster in production, the simulation analysis and the optimization design of related mining project were carried out by using the method of numerical simulation. Finally, we achieve that the promote project of mining from the inside out can reduce the slumping destruction of open-pit slope to ensure the normal advance and safety production of coal face.