Abstract: Lots of CFG piles composite foundations are adopted in construction of pumping stations in order to improve the bearing capacity. Due to the existence of difference between upstream and downstream water levels, cement or clay, instead of granular, is often used as cushion materials. A single pile composite foundation finite element model is establiashed by using ABAQUS program, and the influences of the thickness and deformation modulus of the difference cushion matrials on the pile-soil stress ratio are analyzed. The research results will provide a theoretical evidence for the suitable selection of the cushion thickness and its materials and will be beneficial to the optimum design of composite foundations.