Abstract: The displacement boundary condition was determined according to characteristic of horizontal displacement and structure configuration of fractured covers.The compute formulas for settlement displacement,surface subsidence and surface horizontal displacement were derived and surface subsidence for building groups was determined in accordance with characteristics of the structural form of top rock layers.The results indicate that the surface subsidence is related to relative location between the building and the goaf,that means the surface subsidence about building foundation decreases with the increasing rock and soil mass thickness above the mine goaf with nonlinear characteristics,and in the range of the surface subsidence the horizontal displacements are of even distribution and their directions are against with each other,both towards the building.