This paper is aimed to analyze the structural responses of a scale reactor structure model of a lead-bismuth-cooled ADS reactor under the design seismic time history loads. As a heavy-liquid-metal-cooled reactor, the fluid-structure interaction due to seismic loading is a key issue that may significantly affect the responses of the structures. Two three-dimensional finite element analysis models based mainly on shell element have been built, considering the gap and contact effect between components by nonlinear contact elements with gap specification. The fluid-structure interaction of the structure with an annular cavity in the scale reactor structure was included in the analysis model through a hydrodynamic mass matrix element considering no leakage effect on the ends of the annulus for the first model, and assuming some mass loss due to leakage at the ends for the second model, while additional mass elements due to fluid effect were used for all other structures in both models. Simulation analyses for the scale reactor structure were carried out to obtain the dynamic acceleration response data of the main components, and the comparison with measured data of vibration characteristic tests was conducted, the result showed that considering some mass loss at the ends of annulus would obtain a more precise result. The results of this paper will provide a theoretical recommendation for the design scheme of the subsequent seismic experiment of the scale reactor structure model.