A　high-accuracy　time-domain　formulation　for　the　seismic　hydrodynamic　pressure　on　the　vertical　up-stream　face　of　dam　is　proposed,　which　couples　with　the　dam　finite　element　model　to　consider　the　dam-reservoir　interaction.　The　numerical　model　of　the　semi-infinite　reservoir　is　thus　avoided.　In　frequency　domain,　the　exact　relationship　between　hydrodynamic　force　and　total　horizontal　motion　is　obtained　based　on　the　analytical　solution　of　reservoir　and　the　dam-reservoir　interface　condition.　This　relationship　is　transformed　into　the　high-accuracy　time-domain　formulation　with　auxiliary　functions　by　using　the　temporal　convolution　localization　method　proposed　by　authors.　This　formulation,　in　spatially　and　temporally　discrete　form,　can　be　incorporated　into　the　dam　model,　leading　to　the　dynamic　equations　of　a　dam-reservoir　system,　which　is　solved　by　an　explicit　algorithm　developed　by　authors.　It　is　implemented　by　an　UEL　module　of　ABAQUS　so　that　the　commercial　code　can　be　used　to　analyze　a　seismic　nonlinear　dam-reservoir　interaction　problem,　and　the　UEL　module　can　couple　with　the　dam　model　in　construction　of　the　finite　element　model,　avoiding　any　special　treatment　such　as　restart　in　solution　process.　Application　of　this　new　formulation　to　hydrodynamic　pressure　on　a　rigid　dam　demonstrates　that　the　solution　is　stable　and　agrees　very　well　with　the　analytical　results.　A　seismic　response　analysis　of　Koyna　gravity　dam　is　also　given.　©　Copyright.