Abstract: To study the influences of the characteristics of saturated soils on the horizontal dynamic impedance of a pile, a computational model for the interaction between the saturated soils and the pile is established. First, based on the Biot theory of saturated porous media, considering the existence of the vertical displacement and vertical strain of the soil, using the Helmholtz decomposition law to introduce a potential function, the analytical solutions for the displacement and stress of the saturated soils are obtained. Secondly, using the interaction between the saturated soils and the pile, the vibration differential equation for the pile-saturated soil coupling is established, and then the analytical solutions for the impedance and damping of the pile are obtained. Through a numerical example, compared with those of the existing models, the results of the proposed model are verified. Through the parameter analysis, the influences of porosity, compressibility, and liquid bulk modulus of the saturated soil on the dynamic impedance of the pile head are studied and its corresponding damping effects. It is found that the porosity, compressibility and liquid bulk modulus of the saturated soils have a great influence on the dynamic impedance of the pile head and its corresponding.