In this study, the dynamic interaction (SSSI) of a double tunnel–sand–soil–bridge pile system under earthquakes is investigated by conducting a shaking table test in the context of an actual project in Dalian. The dynamic response laws of the structure and site are determined and compared with the results obtained using ABAQUS numerical simulation. In the numerical model introduces, the Kelvin intrinsic model subroutine is introduced, and the equivalent linear method is used to deal with the nonlinearity of the sandy soil in the calculation process. The experimental results are compared with the results obtained using the numerical model to verify the reliability of the numerical simulation. Based on this, eight working conditions are designed, and the interaction law between the structures in the system is investigated through a comparative analysis. The results showed that the tunnel amplifies the dynamic responses of the bridge pile, adjacent tunnel, and far field, while the bridge pile attenuates the dynamic responses of the side tunnel and far field; the presence of both the tunnel and bridge pile increases the internal force of the adjacent structure, and the peak internal force often occurs near the intersection of the structure or at the pile–soil interface.