The dynamic response of the piles under extreme waves is investigated according to the Codes of Harbor Hydrology( JTJ 213—1998)，we discrete the piles with FEM method and calculate the pile response considering the fluid-structure coupling effect in deep sea water environment. For further researching the pilesoil interaction, we carry out a comparative analysis with that under different pile-soil conditions. Results show that the pile-soil interaction has a great impact on the pile response in the open sea environment. The pile response under saturated soil has an error of 10% comparing with that under simplified impedence.