Abstract: In the composite foundation,the pile,soil,cushion and pile cap were considered as an interacting foundation system.In consideration of the friction between the soil and the piles,nonlinear character of soil,main effect of each part in the system and their interrelationship,the composite foundation and it′s bearing mechanism and the stiffen effect were studied by the three-dimensional finite element numerical analysis.At first,the load transfer character of the single pile was analyzed,then the lateral friction of the pile,the stress on the pile top and the distribution of the stress in the pile of the composite foundation were studied.Finally,some results would be profitable and helpful to the theoretical analysis and the engineering design.