Based　on　the　shaking　table　test　of　the　liquefiable　soil-piles-superstructure　system,　the　liquefaction　process　and　seismic　failure　mode　of　the　liquefiable　site　with　an　overlying　non-liquefiable　soil　layer,　as　well　as　the　instability　or　damage　mechanism　of　a　low　pile　cap-pile　group-superstructure　system　are　analyzed　by　a　two-dimensional　finite　element　model.　The　model　considers　the　post-liquefaction　shear　deformation　of　sand,　the　interface　models　for　the　pile　and　cap　with　the　liquefiable　and　non-liquefiable　soil,　and　the　interface　model　between　the　liquefiable　and　non-liquefiable　soil　to　account　for　the　discontinuity　of　interface　deformation.　The　typical　calculation　results,　including　the　excess　pore　pressures,　accelerations,　displacements　of　soil,　and　bending　mo-ments　of　the　piles,　are　compared　with　the　experimental　results　to　verify　the　developed　models　and　reveal　the　effects　of　site　liquefaction　and　the　soil-structure　dynamic　interaction　on　the　seismic　responses　and　instability　mechanisms　of　the　piles-superstructure　system.