A　numerical　model　for　the　structure-water-soil　(layered)-rock　(SWLR)　system　is　proposed　in　this　paper　to　evaluate　the　system　dynamic　response,　in　which　the　fluid-solid　coupling　effect　is　considered　by　the　interface　conditions　and　the　wave　radiation　effects　of　far-field　domain　are　simulated　by　artificial　boundary　conditions.　Moreover,　this　model　covers　four　prime　respects,　including　the　discretization　of　interface　conditions,　the　absorbing　boundary　conditions,　the　equivalent　earthquake　loading　input　and　the　general　finite　element　equation.　It　can　be　solved　by　a　standard　time　integration　algorithm　such　as　implicit　Newmark＇s　method.　Furtherly,　the　effectiveness　of　the　proposed　model　is　verified　by　three　numerical　examples.　Apart　from　these,　the　dynamic　stiffness　matrix　method　(DSM)　of　fluid　and　solid　adopted　in　present　study　to　acquire　the　equivalent　earthquake　loading　effectively　accomplishes　the　oblique　incidence　of　the　wave　in　layered　half-space　with　arbitrary　angles.　Based　on　the　proposed　model,　the　effects　of　dynamic　water-structure　interaction　(WSI)　and　soil-water　interaction　(SWI)　on　the　seismic　responses　of　offshore　structure　are　investigated,　which　is　conducive　to　the　simplified　analysis　of　dynamic　fluid-solid　interaction　and　the　design　of　ocean　engineering.