Abstract: In order to study the influence of the rigid pile composite foundation on the lateral soil pressure of adjacent supporting structures, prior to the design of the indoor model test scheme, the models of the adjacent natural foundation and the composite foundation are built by the finite element software for the numerical simulation, and the soil pressure distribution on the static retaining wall side under different foundation forms is estimated. The comparison of the numerical simulation results of the two groups shows that the soil pressure distribution of the composite foundation is different from that of the natural foundation. When the soil stress between the piles under the composite foundation cushion is the same as that of the natural foundation soil, the additional effect of the natural foundation on the wall side soil pressure at the same position of the retaining wall is significantly greater than that of the composite foundation, but as the "load transfer effect", the influence of the composite foundation on the lateral earth pressure of the retaining wall is gradually transmitted to the deeper soil as the load increases. It can be clearly seen that compared with the natural foundation, the effect of the composite foundation on the lateral earth pressure of the retaining wall is relatively weaker in the shallow soil layer, but stronger in the deep soil layer, and the stress concentration at the pile end has a significant effect on the lateral soil pressure at the bottom of the retaining wall.