Abstract: The ecological environment of the modern Yellow River delta wetland is getting more vulnerable under the influence of sea level rise, storm tide, shortage of discharge, extreme precipitation or evaporation, as well as human activities. A coastal wetland groundwater model was constructed by using Cl- as a simulated factor. The results suggest that the change in shallow groundwater quality of the wetland depends upon the natural factors such as strong cutoff in the lower reaches and storm tide and human engineering activities. The coastal wetland would be submerged in the north without damp proof when the height of the storm tide reaches 2.4 m. The depth gradients of shallow groundwater and brackish water in sediments in the studied coastal delta wetland are the key factors to the vulnerability of ecological environment. The desalination of brackish water is derived by the joint action of groundwater dynamics, hydrochemistry and ocean tidal process.