In order to study the mechanical characteristics of the cantilever retaining structure in the excavation process of the foundation pit,we combine with the deep foundation pit engineering of a large second ship lock,analyze the displacement of the row pile and the variation law of earth pressure during the excavation process by the centrifugal model test,and apply the numerical simulation method to verify and analyze the distribution and change of bending moment and shear force of the pile body during excavation.The results show that the earth pressure on the retaining side of the pile foundation is close to the static earth pressure state in the consolidation period,the theoretical value of the active earth pressure is close to the second foundation pit excavation,and the earth pressure is gradually reduced during the foundation pit excavation process.Due to the influence of foundation pit excavation,the soil on the side of the foundation pit is destroyed by the support pile extrusion,the earth pressure is redistributed,and the earth pressure in the passive zone at the same depth is greater than the earth pressure in the active zone,the bending moment of the pile body is due to the earth pressure.The “C” shape distribution law is presented by the influence of the difference,and the shear force exhibits the “S” shape distribution law.The maximum bending moment and the shear force abrupt position are moved downward toward the pile body as the foundation pit is excavated.