Abstract: A coupling finite-infinite element method is proposed to calculate the stress and deformation of pile-subsoil coupling systems under large deflection. A new kind of interface elements with thickness is inserted in the interface between the soil and pile, which can dovetail with elastoplastic models of soil and reflect the deformation in the interface and its nearby shear failure area reasonably. The result of an example is reasonably in accord with data of on-site observation, verifying the feasibility of the proposed method.