This　study　presents　underwater　explosion　tests　with　three　different　TNT　charge　weights　to　investigate　the　dynamic　responses　of　a　fixed　steel　sheet.　A　finite　element　model　was　established　and　benchmarked　by　comparing　the　bubble　development　and　deformation　distribution　from　the　tests.　The　steel　sheet　shows　a　deformation　process　of　hogging,　sagging,　and　hogging　again,　due　to　the　actions　of　shock　waves,　bubble　expansion,　bubble　collapse,　and　bubble　pulsation.　The　air　may　be　sucked　into　the　bubble　during　the　hogging　process,　making　the　bubble　collapse　earlier　and　resulting　in　a　relatively　lower　sagging　deformation　for　large　charge　weights　of　TNT.　The　deformation　caused　by　bubble　pulsation　is　larger　than　that　by　the　shock　waves,　owing　to　the　large　time　duration　of　bubble　pulsation.　A　parametric　analysis　was　conducted　to　study　the　influence　of　steel　grade,　plate　thickness,　detonation　distance,　and　the　shape　and　position　of　charges　on　the　dynamic　behavior　of　steel　plates　subjected　to　underwater　explosions.　It　shows　that　the　damage　to　the　steel　plate　gradually　decreases,　with　the　increase　in　steel　strength,　plate　thickness,　and　detonation　distance.　The　influence　of　the　shape　and　position　of　charges　is　limited.　The　largest　deformation　is　observed　when　the　detonation　distance　increases　to　bubble　radius.　©　2022　by　the　authors.