Abstract: The penetration of pile is modeled as a sphere cavity expansion process. On the basis of the spherical cavity expansion theory, this paper proposes the analytical solution of the stress, displacement and excess pore water pressure in the whole field of soil around the pile. The concerned field comprises elastic zone, plastic zone and failure zone after the sphere cavity expansion in saturated clay. The solution adopts large-strain presupposition, the modified Cambridge model, and the theory of water power cracking, and follows the least consumption principle. The effect of soil’s over-consolidation ratio is investigated. The validity of the proposed solution is verified by a comparison with other references. It can provide theoretical supports for some geotechnical engineering practices in saturated soil, such as jacked pile, driving pile, and so on.