Abstract: Small nuclear reactors have become a research hotspot due to their wide range of applications. However, tehy are usually partially or completely buried, which makes soil-structure interaction have a profound impact on their seismic responses. Considering the soil-structure dynamic interaction can more realistically reflect the response characteristics of nuclear power plant buildings on soil sites under earthquakes, which can help evaluate the safety of nuclear power equipments under earthquakes, and is crucial to ensure the reliability and safety of the nuclear power plant system. By using the numerical simulation methods, three typical sites and a representative small nuclear reactor structure are selected as the research objects, and the floor response spectral characteristics of small nuclear reactors are explored under different structural burial depths and different floor heights. The research results show that after considering the soil-structure dynamic interaction, the peak frequency of the floor response spectra of small nuclear reactors will shift to low frequency. The stiffness of the site soil layer has a significant impact on the floor response spectra. After considering the soil-structure interaction, the amplitudes of floor response spectra decrease with the decrease of the structural floor height, and the amplitude decreases in the low-frequency range and increases first and then decreases in the medium-high-frequency range.