Abstract: In order to reasonably estimate the longitudinal seismic responses of shield tunnels, the shield tunnel is regarded as a Timoshenko beam resting on a Pasternak elastic foundation. Considering the axial force and the abrupt change in stiffness, a theoretical calculation model under the joint action of longitudinal and transverse strata displacements is proposed and solved by finite difference method. The theoretical solutions are compared with the numerical simulation results to verify its validity and reliability, then the influences of six key parameters on the longitudinal seismic response are further explored. The increase in shield tunnel stiffness can effectively improve the seismic performance of the tunnel. However, in the vicinity of the stiffness variation, the segments with relatively small tunnel stiffness (regular or degraded segments) may experience higher local deformation under seismic actions. Reducing the longitudinal stiffness ratio and shortening the length of strengthening section can significantly mitigate the adverse seismic response of tunnel lining caused by abrupt change in stiffness. The local deformation at the tunnel is positively correlated with the foundation reaction coefficient, and the local deformation increases and then decreases with the increase of wavelength. Seismic waves with wavelengths between 20 m and 120 m are more likely to lead to larger opening and dislocation, on the scenario of higher foundation reaction coefficient. The residual axial force can improve the seismic performance of shield tunnel to a certain extent, especially when the angle of incidence and tunnel stiffness are relatively small.