This paper presents a three-dimensional numerical simulation method for the seismic response of piles in liquefiable soils using a unified plasticity model for large post-liquefaction shear deformation of sand. The unique constitutive model used is able to achieve unified description of the behavior of sand at different states under monotonic and cyclic loading during both pre- and post-liquefaction regimes. In the finite element analysis, soil is modelled through u-p form coupled brick elements and pile through second-order brick elements. Centrifuge shaking table experiments on single piles in level liquefiable ground, and on single piles in lateral spreading ground was simulated using the proposed finite element analysis method. Simulation results exhibits the method’s effectiveness in reproducing the dynamic response of both the ground and piles.