Abstract: Taking Laohutai subsidence area as an example, for the problem that the differential settlement of bad foundation in subsidence area can not meet the requirements of the use of foundation, finite element method is used to carry out numerical simulation study, that is using CFG pile to carry out foundation treatment, the building before and after CFG pile reinforcement and the deformation of foundation soil are systematically analyzed. The results show that the stability of foundation has been greatly improved after strengthening with CFG piles, the overall subsidence of the building is obviously reduced, and the horizontal displacement is very small. The feasibility and safety of differential settlement of bad foundation by CFG pile in settlement area are verified. For the bad foundation that the bearing capacity is large enough, but the foundation difference settlement is too large, using CFG pile to coordinate ground deformation has good effect.