A three-dimensional finite-difference groundwater flow model was implemented to investigate the seawater intrusion problem of the new campus of Dalian ocean university under condition of variable density. The modeling package SEAWAT witch was employed in the Visual MODFLOW was applied for this purpose. Two different scenarios with and without the seepage-proof wall that was set along the north boundary of the schoolyard were considered to predict the groundwater table distribution and the salt concentration distribution and their respective variation under different conditions. The simulation results show that the groundwater table distribution and the salt concentration distribution and their variation are rarely affected by the seepage-proof wall. The salt enters the new campus and reaches a high level eventually.