The soil compaction effect of pile penetration increases earth pressure on the pile shaft. Analyzing earth pressure changes caused by pile penetration is significance for establishing a calculation method for pile penetration resistance. The large deformation numerical simulation method and the NHRI soil model were used to analyze the pile penetration process in sandy soil. The variation of earth pressure coefficient K under different working conditions was analyzed. Numerical analysis results indicate that the change in soil horizontal stress during the pile penetration process can be divided into three stages: loading, unloading and stress stabilization. The soil horizontal stress peaks when the pile end reaches a certain depth, and then the soil enters the unloading stage as penetration continues, and finally stabilizes. The maximum disturbance range is 5D in the depth direction and 6D in the radial direction. Earth pressure on the pile shaft after penetration is approximately linear, with extreme values at the pile end. The change in pile diameter has an insignificant effect on earth pressure, and the earth pressure on the pile shaft with different diameters is similar. As the interface friction coefficient increases, the earth pressure on the pile shaft gradually rises. Based on the numerical analysis results, a method for calculating pile shaft earth pressure considering the pile-soil interface friction coefficient is proposed.