According　to　the　theories　of　wave　propagation　in　visco-elastic　continuum　and　Rayleigh-Love　rod,　a　simplified　model　in　axisymmetric　conditions　for　the　longitudinal　vibration　of　large-diameter　pipe　pile　(LDPP)　in　radially　heterogeneous　surrounding　soil　with　viscous　damping　is　presented.　The　relevant　analytical　solution　for　dynamic　impedance　at　pile　head　is　derived　by　using　complex　stiffness　transfer　method,　which　is　also　validated　via　independent　comparisons　with　previous　solutions.　Besides,　parametric　analyses　are　carried　out　to　reveal　both　the　radial　heterogeneity　of　surrounding　soil　and　the　lateral　inertia　effect　of　pile　shaft　on　the　dynamic　impedance　of　LDPP.　The　obtained　analytical　solutions　are　suitable　for　the　longitudinal　vibration　issues　of　floating　LDPP　in　visco-elastic　surrounding　soil　with　radial　heterogeneity,　which　can　be　conveniently　degenerated　to　describe　the　longitudinal　vibration　of　a　floating　solid　pile　in　soil　with　radial　heterogeneity　as　well　as　a　floating　LDPP　or　solid　pile　in　radially　homogenous　soil.