Three-dimensional finite element model of a nuclear power plant structure was established and the seismic response simulation of the model was carried out by the ACS SASSI software for 3D dynamic analysis of the soil-structure interaction. Compared with the simplified lumped‑mass stick model， the three-dimensional finite element model can more truly reflect the dynamic characteristics of the structure， especially the local vertical modes of the structure， although the vibration characteristics of the two models are similar in the horizontal direction. Nine different shear velocity values in the range of 400-2400 m/s were selected for the seismic response of nuclear power plant structure under different site conditions by the ACS SASSI software. The results show that： with the increase of site shear wave velocity， the predominant spectrum components of the structural response have the tendency to move to the high frequency section； in the low frequency part， the seismic response of the structure on the site with small shear wave velocity is larger； in the high frequency part， the seismic response of the structure with large shear wave velocity is larger； for non-bedrock site， it is necessary to pay attention to the low-frequency response of the structure. In a certain range of shear wave velocity， the peak acceleration and the peak value of floor response spectrum of the structural response increase with the increase of the site shear wave velocity， and the peak acceleration is more sensitive to the site with smaller shear wave velocity.