Abstract: A multi-objective simulation-optimization groundwater management code, namely MOSWTGA, is developed by coupling an improved genetic algorithm (adding probabilistic niched technique and the Pareto solution set filter) with a density-dependent groundwater flow and solute transport simulator, SEAWAT, to obtain the optimal strategies for utilization of groundwater resources. The MOSWTGA is used to solve the multi-objective simulation-optimization model for optimal groundwater abstraction strategies while preventing the pumping aquifer from seawater intrusion in the Zhoushuizi district of Dalian, and a set of Pareto near-optimal solutions of tradeoffs between the maximization of the total pumping rate and the minimization of the extent of seawater intrusion are obtained. This study, based on the real hydrogeology parameters and groundwater abstraction conditions, provides a practical framework for implementing a reasonable allocation of groundwater resource, as well as an efficient and reliable tool for solving density-dependent groundwater optimization management models associated with multiple objectives, potentially leading to significant environmental and economic benefits.