Abstract: The lateral vibration of the soil under SH harmonic seismic waves is solved by one-dimensional model of wave motion. On the basis of three-dimensional soil model and taking consideration of wave effect of soil, the radial displacement and horizontal displacement caused by pile-soil interaction and the lateral soil force on the pile are obtained by means of the potential functions and variable separation method, and the lateral dynamic equation of the pile is established by considering the orthogonality of trigonometric function and the continuous conditions at the soil-pile contact surfaces. The influence of the SH harmonic seismic waves on the horizontal displacement of the pile head is investigated by the concept of magnification factor. The results indicate that the dynamic response of the pile under SH harmonic seismic waves has resonance. There are three peaks of the curves of amplification factor versus frequency, and the first two peaks are relatively larger. The pile-soil modulus ration has little effect on the amplification factor when the pile-soil modulus ration is larger.