Abstract: The local inflow is an important factor affecting the accuracy of hydrodynamic models, but its value is difficult to determine and quantify in real-world applications.From the viewpoint of inverse problems, a method is proposed to determine the local inflow.Firstly, the continuity equation is integrated along the reach to have the analytic expression of inflow correction, and then the response function between the nodal stage and the local inflow can be obtained by numerical discretization.Finally, based on observed tidal data, the local inflow is evaluated by the iterative algorithm.A numerical experiment is conducted to validate the feasibility of the proposed method.Excellent agreement is obtained between the inverse values and the real ones as revealed by the deterministic coefficient of 0.996.The method is applied to the hydrodynamic modeling of the reach from Datong to Zhenjiang in the Yangtze River.The generalized process of local inflows in the reach is obtained and further refined.The result demonstrates the validity of the method.