Abstract: The paper revealed some faults of FEMs for soil-s tructure interaction p roblems. On the base of subtle analysis of the soil-structure interaction mechan ism, it was suggested that in the soil-structure integral FE models displacement of all the nodes on the interface will be affected by the deformation mode of s tructures because of the big stiffness difference between the structure and soil . Hence the critical point of the numerical simulation of soil-structure interac tion lies in how to process the above nodal displacement constraint conditions.F inally,two new FE models of pile and raft structures have been presented in the paper by using generalized freedom methods.