Based on a practical engineering site profile of Chengdu area, we studied the effect of different seismic wave inputting interfaces on the results of the soil layer seismic response. We found that both the peak ground acceleration and the characteristic period increased with the increase of depth of seismic wave inputting interface.The peak acceleration was increased by more than 20%, the characteristic period was increased by more than 10%.This conclusion can provide reference for seismic design engineers.