To　investigate　the　extent　of　seawater　intrusion　in　the　Liao　Dong　Bay　coastal　plain,　China,　a　numerical　model　for　variable-density　groundwater　flow　and　miscible　salt　transport　was　developed.　The　SEAWAT　code　was　used　to　solve　the　density-dependent　groundwater　flow　and　solute　transport　governing　equations.　The　simulation　was　conducted　for　55　months　from　October,　2004　to　April,　2009.　The　numerical　model　was　calibrated　by　the　hydraulic　heads　measured　in　April,　2009.　Using　the　calibrated　model　and　the　same　hydrogeological　conditions　in　2004,　the　extent　of　seawater　intrusion　prediction　was　conducted　for　the　next　40　years.　The　results　show　that　the　extent　of　seawater　intrusion　area　will　increase　in　all　geologic　layers　with　nearly　6.2　km　in　the　upper　Quaternary　aquifer　and　4.3　km　in　lower　Quaternary　aquifer　for　40　years.　In　the　Minhuazhen　group　aquifer,　the　maximum　speed　of　seawater　intrusion　is　62.2　m/yr.　Therefore,　some　protection　of　the　freshwater　aquifer　from　seawater　intrusion　in　the　Liao　Dong　Bay　coastal　plain　is　imperative.