Abstract: Calculations of the designed thickness of cushions in composite foundation with rigid piles are further studied.According to the present achievements on the stress field of composite foundation with rigid piles,the stress field is simplified and the thickness of cushion with negative friction taken into account is deduced,based on the harmonious deformation conditions between piles and soil.Meanwhile,the stress analysis of cushions is carried out and the thickness is deduced again based on the equilibrium condition of stress,neglecting the negative friction.Then a comparison of the two calculations is made and the proposed thickness of cushions in composite foundation with rigid piles is put forward for a reference.