<p>The damage effects of the earthquake on tunnels crossing faults are categorized into two types: inertial forces generated by ground motions and permanent stratigraphic deformations caused by fault dislocations. A seismic dynamic analysis method of tunnel considering coseismic dislocation is proposed by introducing the numerical simulation of seismic wave propagation into the soil–structure dynamic analysis research field. First, seismic waves are simulated according to the finite-difference method. The stress, displacement, and velocity of nodes on the truncated boundary of the soil–structure model can be calculated according to the seismic wave propagation simulation method. Then, the seismic waves and dynamic dislocation load are simulated in the finite element model by the viscous–spring boundary. Based on the free-field model, the reliability of the presented method is validated in simulating coseismic deformation and seismic waves. In the case of the 2022 <i>M</i>_S 6.9 Menyuan earthquake and the Daliang tunnel, which was severely damaged by this earthquake, the deformation of the tunnel simulated based on the presented method is consistent with the previous method. The proposed method can offer guidance for the seismic fortification of tunnel engineering.</p>