In this paper, an emergency bridge was first built in a nuclear power plant to meet constructional, operational, and emergency needs, as seismic safety is very important. In this paper, the finite element dynamic time-history analysis method was introduced to construct a three-dimensional integral refined model considering bridge-pile-soil interaction. Maximum acceleration of typical subgrade section and T beam, and distribution of the maximum moment at the bottom of a bridge pier column were calculated under SL-1 and SL-2 earthquake actions. Calculated results showed that this method can directly address the nonlinear problem of soil and conveniently incorporate the radiation damping effect of the foundation. Contact between T beam and cover beam can be precisely simulated. Moreover, the independent development high-performance software platform GEODYNA, with its high efficiency, was used for 3D calculation. This method can provide some reference in the seismic design of bridges in nuclear power plants.