With the geological change of some mine in Inner Mongolia, south side with deformation and slide, causing potential safety hazard, the slowing side angle deepened the buried coal, the west mining and northwest mining were put forward. By comparison, the strip northwest mining was better. Rock stress and displacement changing law under different width protective coal column were got by FLAC 3D numerical simulation, which ensured the width of protective coal column and the position of stopping mining line, provided theoretical basis for strip mine combined mining.