In this paper, the internal force law of the south bank section and wind tower structure of Dalian Bay subsea immersed tube tunnel under the action of earthquakes and the structural damage characteristics in the elastoplastic stage were studied. In addition, a three-dimensional refined model of an immersed tube-plant-wind tower was established, and the ABAQUS built-in constitutive model of concrete damage was used to perform seismic response analysis of the structure under two seismic conditions using mode-superposition response spectrum and time-history analysis methods. Results show that the maximum displacement values in the X and Y directions are 1.11 and 5.56 mm, respectively, both appearing at the top of the structural ventilation tower. Moreover, the modal mass participation coefficients in the X and Y directions are 90.52% and 92.07%, respectively, both meeting the requirement of seismic code, and the bending moment at the junction of two lanes of the immersed tunnel is the largest, reaching 5 069 kN·m. Under rare earthquakes, the maximum story drift ratio of the structure is 1/2 798, and the maximum damage of the structure appears at the time of seismic wave peak. By observing the damage, the structural concrete is uniform, and no broken phenomenon is observed. The maximum tensile damage coefficient is 0.893-0.94, appearing at the fresh-air duct and roof of the fresh-air room. Therefore, enhancing the bending resistance at the connection between the two lanes of the immersed tunnel and adding reinforcement at the top plate of the fresh-air duct and fresh-air room are necessary to improve the tensile capacity.