Abstract: Two groups of artificial ground motions that are compatible with the hydraulic standardized response spectrum, were input to a high arch dam to study the influence of peak ground displacement (PGD). The two different groups produced the same peak value in acceleration and velocity but different displacements. To demonstrate different seismic responses, we have adopted a time-domain wave method that couples an explicit finite-element method with viscous-spring artificial boundary conditions, and applied it in a case study of the Xiaowan arch dam, using the two groups of artificial motion histories as the exciting SV waves of incidence and observing the influence of PGD on the arch dam-foundation rock system. The results show that the PGD of this dam has great effect on the principal stress in dam body, the arch stress in arch abutments, and the vertical stress at the bottom of crown cantilever, and that its effect on the stream-wise displacements is also quite significant. Thus, the PGD should be accounted for in seismic safety evaluation and design of high arch dams.