The　offshore　structures　of　single　pile　foundation　may　suffer　serious　damage　under　seismic　action　because　of　the　complex　marine　environment.　In　order　to　solve　the　dynamic　response　of　the　pile　foundation　under　seismic　action,　a　simplified　analytical　solution　for　water-pile-soil　interaction　system　considering　elastic　half-space　of　soil　under　seismic　action　is　established.　Firstly,　the　pile　is　assumed　to　be　viscoelastic　material,　which　can　be　divided　into　multiple　pile　segments　in　the　water-pile-soil　interaction　system.　The　soil　and　water　are　assumed　to　be　linear　viscoelastic　medium　and　acoustic　medium　respectively.　Then,　based　on　the　Helmholtz　decomposition,　separation　of　variables　and　water-pile-soil　continuity　condition,　the　displacement　expression　of　the　whole　pile　is　obtained.　Then,　the　analytical　solution　is　degenerated　into　two　cases,　and　compared　with　that　of　the　substructure　method　in　the　case　of　soil　without　water　and　the　rigid　analytical　solution　in　the　case　of　soil　with　water　so　as　to　verify　the　rationality　of　the　elastic　analytical　solution.　Finally,　some　parameters　are　analyzed　by　using　this　elastic　analytical　solution　to　study　the　influences　of　three　parameters,　namely　water,　soil　and　pile,　on　the　dynamic　response　of　pile　displacement.　The　research　results　are　of　certain　reference　value　for　the　design　of　offshore　pile　foundations.　©　2023　Chinese　Society　of　Civil　Engineering.　All　rights　reserved.