With　the　engineering　constructing　in　the　karst　area,　there　is　a　serious　problem　on　the　thickness　of　the　security　and　deformation　of　the　cave　roof.　In　this　paper,　it　conclusive　the　degree　of　the　karst　development　not　only　influenced　by　the　structure　of　earth　but　also　influenced　by　the　type　of　rock　and　groundwater.　The　collapse　of　the　karst　is　influenced　by　the　development　of　the　karst　thickness　of　the　quaternary,　the　intensity　of　the　mining　groundwater　and　water　level.　Based　on　getting　the　relevant　physical　mechanical　parameters,　the　finite　element　model　of　the　karst　development　foundation　is　established　by　the　numerical　simulation.　Simulating　the　dept　of　the　influence　of　the　foundation.　It　is　meet　the　building　foundation　specification　deformation　when　the　dept　of　the　karst　area　is　dealt　about　7m.　Meanwhile　checking　with　the　semi-quantitative　analysis,　the　conclusion　is　consistent　with　the　results　of　the　numerical　simulation.　The　results　show　that　the　analysis　has　a　better　prediction　precision,　reliable　and　reasonable.　It　is　an　effective　new　way　to　the　engineering　construction　in　the　karst　area.　©　2015　ejge.