In order to study the dynamic response of PHC pipe piles on the liquefied sandy soil foundation under earthquake,we apply FLAC3D finite difference software to establish soil,solid PHC pipe pile and equivalent mass at pile top as superstructure considering the coupling among the water body,the soil and the PHC pipe pile,and study the liquefaction of the soil,the deformation of the site and the response of the PHC pipe pile by the application of seismic loads at the bottom of the model for complete nonlinear dynamic analysis.The results show that the effective stress of saturated sand decreases due to seismic action,and liquefaction occurs in all height of sand.The occurrence and time of liquefaction are not only related to the buried depth of soil,but also to the sequence of seismic loads and the peak acceleration of seismic loads.The normal stress of pile embedded in soil increases first and then decreases,and the maximum value appears at the junction of slope protection and sandy soil.The lateral displacement of pile in shallow depth is larger than that in deep depth.The displacement and internal force of PHC pipe piles under strong earthquake are both large,and it is necessary to improve the liquefaction site before the construction of the wharf.