To predict the impact of regulation project on the tidal prism，tidal level and velocity at the Guanhe estuary and provide the optimal regulation plan of the Guanhe estuary，we analyze the natural conditions of the estuary firstly，then build a two-dimensional mathematical model，which is verified by measured filed data，and finally analyze the changes of hydraulic characteristics after the project by the mathematical model.The result shows that waterway dredging project should be carried out with the regulation project because leading jetties can decrease the tidal prism significantly；After implementation of the leading jetty engineering and waterway engineering，the velocity of the flow between the double jetties increases.