Abstract: The pumping groundwater, the changing sea level and the rainfall recharge affect the extent of seawater intrusion in the coastal aquifers. With continue change of the future climate, predicting the impact of future climate change on the extent of seawater intrusion can provide a basis for the rational allocation of regional water resources. The calibrated three -dimensional heterogeneous density -dependent numerical model which was constructed by using SEAWAT was applied to predict the impact of future rainfall scenarios including different rainfall frequency analysis and climate modes derived from CMIP5 (Coupled Model Intercomparison Project Phase 5) on the extent of seawater intrusion in Zhoushuizi district of Dalian City in northern China. The results show that the extent of seawater intrusion in the future is negatively correlated with the future rainfall，namely the less rainfall, the more severe extent of seawater intrusion.For example, the extent of seawater intrusion in dry years is more severe than that in normal years and wet years. Among the seven climate modes, the future average annual rainfall of MPI climate mode (S7 -2 -Y)is the minimum, so the extent of seawater intrusion in the future is also the most severe.In the CNRM climate mode (S5 -2 -Y), the future average annual rainfall is the maximum, so the extent of seawater intrusion in the future is the least severe.And, the extent of seawater intrusion is almost identical to each other for different greenhouse gas emission scenarios of every climate mode.Overall, the extent of seawater intrusion in the future would be even more severe.The establishment of the prediction model can guide the actual water resources allocation of similar coastal areas in China.