A three-dimensional nonlinear elastic-plastic finite element method had been developed to study the bending behavior of piles subjected to axial load and lateral soil displacement. The influence of the lateral soil displacement, axial load level and the cap of piles were studied and variety law of the bending behavior was presented. The study showed that the bending moment increased with the lateral soil displacement. The displacement at the soil surface and the maximum bending moment of pile also increase with the axial load. The cap of piles has a great influence on bending moment and displacement of pile group.