Abstract: The evaluation for foundation stability should be done before the construction of buildings above the goaf, then appropriate measures should be taken according to the actual situation. In many different treatment programs, grouting reinforcement is the most direct and effective measure. The paper, combined with the mechanisms and problems involved in grouting reinforcement, analyzes the advantages of FLAC^3D in this field, and makes simulation analysis about goaf grouting problem by FLAC^3D.