The　longitudinal　seismic　response　of　a　long　tunnel　subjected　to　Rayleigh　waves　is　investigated　in　this　paper.　The　tunnel　is　assumed　to　be　infinitely　long,　has　a　uniform　cross　section,　and　rests　on　a　viscoelastic　foundation.　The　free-field　deformation　under　Rayleigh　waves　traveling　parallel　to　the　tunnel　axis　is　decomposed　into　two　directions,　namely,　the　axial　motion　and　the　vertical　motion,　and　transformed　into　dynamic　loads　imposed　on　the　tunnel.　Based　on　the　Fourier　and　Laplace　integral　transform　techniques,　the　governing　equations　of　tunnels　are　simplified　into　algebraic　equations,　and　the　analytical　solutions　are　obtained　with　the　convolution　theorem.　The　final　solutions　of　the　tunnel　responses　in　terms　of　deflection,　velocity,　acceleration,　axial　force,　bending　moment,　and　shear　force　are　investigated.　The　proposed　solution　is　verified　by　comparison　of　its　results　and　those　from　the　finite　element　program　ABAQUS.　Further　parametric　analysis　is　carried　out　to　investigate　the　influence　of　soil-structure　relative　stiffness　ratio　and　wave　frequency　on　dynamic　longitudinal　responses　of　the　tunnel.