Abstract: In order to study the traveling wave effect on seismic response of hydropower house structure with a large plane scale, a three-dimensional finite element model of an actual powerhouse structure is created. The dynamic structural analysis is carried out with ABAQUS software, using modal superposition time-historic analytical method. Koyna earthquake transverse ground acceleration is selected as seismic load, whose peak value is adjusted to 0.246g. The result shows that traveling wave mainly affects the peak value concerning dynamic displacement of powerhouse structure. On condition that the wave speed is small, the peak dynamic displacement may decrease by 25% at the most. With regard to acceleration, the effect on peak value and time history is significant. The peak structural acceleration may lag behind the peak seismic acceleration due to a small wave speed. Ignoring the traveling wave effect is safe to structural design of powerhouse. If the earthquake wave speed at the project site is small, the traveling wave effect can be taken into consideration properly to optimize structural design.