Abstract: The river system in the Pearl River delta is the typical tidal network,and influenced by the surface runof and the t ide level of South Sea Since the middle of the 1980s,large scale of sand excavation has resulted in the great changes of the fluvial process and the hydrological conditions. Based on the hydrodynamics features,this paper builds a one-dimensional hydrodynamic mathematical model to simulate the variat ion of water level and flow rate in the tidal river network. By the Grey Model,the riverbed evolution in the future is predicted By using the hydrodynamics numerical model,the impact of the artifi cial sand excavation on hydraulic features,such as water level and flow rate,is respectively analyzed in high flow and low waterperiods Furthermore,the impact of sand excavation on navigation,irrigation,salt intrusion and water environment are preliminarily assessed.