Abstract: Based on the mechanism of vacuum preloading and the consolidation theory for ground improved by PVD/sand drains improved ground,with equivalent vertical hydraulic conductivity, the ground can be converted into multi layered homogeneous subsoil, and a simplified method for vacuum combined with surcharge preloading is proposed. By comparing with the measured data and conventional FEM analysis in two case histories, the simplified method is verified and is more convenient to be used in engineering design.