In　order　to　give　an　insight　into　the　seismic　responses,　pile-soil　interactions　as　well　as　failure　modes　of　PHC　pipe-piles　in　the　coastal　soft-soil　area,　tests　on　the　PHC　piles-soil-structure　model　system　under　the　shaking　table　were　conducted.　Different　prestress　ratios　and　soil　properties　were　considered　to　investigate　the　influence　on　seismic　response　and　failure　mode　of　PHC　pipe　pile-soil-structural　model　system　by　increasing　the　peak　values　and　inputing　three　different　earthquake　waves.　The　results　indicate　that　soil　saturation　has　a　significant　effect　on　the　dynamic　parameters　and　seismic　responses　of　the　model　system,　and　the　prestress　ratio　has　a　certain　influence　on　dynamic　properties.　The　failure　modes　are　different　as　for　the　unsaturated　soil,　the　natural　frequency　of　PHC　model　system　slightly　decreases　under　the　basic　intensity.　While　for　saturated　soil,　the　natural　frequency　of　model　system　decreases　to　50%　of　the　initial　frequency　with　the　increase　of　peak　ground　acceleration　(PGA),　which　indicates　that　the　model　has　damage　or　even　failure　under　the　rare　intensity.　Moreover,　the　damping　ratio　and　interaction　of　structure-soil-pile　of　PHC　model　will　increase.　However,　the　existence　of　prestress　can　significantly　mitigate　the　effect　of　earthquake.　In　addition,　the　pore　water　pressure　increases　to　1.0　and　is　liquefied　with　the　increase　of　PGA　and　the　soil　depth,　and　the　duration　of　liquefaction　is　far　longer　than　the　seismic　wave　history.　The　results　can　provide　the　basis　for　the　application　of　PHC　pipe-piles　in　coastal　soft-soil　area　and　the　implementation　of　seismic　code.　©　2017,　Editorial　Department　of　China　Journal　of　Highway　and　Transport.　All　right　reserved.