This　study　aims　to　analysis　the　longitudinal　seismic　responses　of　circular　tunnels　across　soil-rock　stratum　longitudinally　(＂soil-rock＂　means　two　different　stratums,　not　just　the　soil　and　rock　ground).　Based　on　an　improved　elastic　foundation　beam　model,　an　analytical　solution　is　derived　to　investigate　the　seismic　response　of　long　tunnels　across　soil-rock　stratum,　subjected　to　sinusoidal　shear　motions.　The　improved　elastic　foundation　beam　model　adopts　the　Timoshenko　beam　and　Winkler　foundation,　with　considering　tangential　contact　conditions　at　the　ground-tunnel　interface.　The　free　field　reaction　considers　the　reflection　and　transmission　by　the　soilrock　interface　and　the　wave　passage　effect.　Explicit　formulations　are　obtained　for　tunnel　displacement,　rotation　angles,　bending　moments　and　shearing　forces.　The　proposed　solution　is　verified　by　comparing　with　the　dynamic　numerical　results,　as　well　as　traditional　analytical　solutions.　Finally,　a　parametric　study　is　conducted　to　investigate　the　influence　of　traveling　wave　effect,　earthquake　frequency,　shear　wave　velocity　ratio　of　two　stratums,　lining　stiffness　and　contact　condition　on　tunnel　seismic　responses.　The　proposed　analytical　solutions　can　be　used　to　predict　the　longitudinal　seismic　response　of　deep　circular　tunnels　crossing　soil-rock　stratum　in　engineering　design.