Abstract: Aiming at the difficulties such as wide range of water supply operation, diversified water conservancy facilities and complex engineering operation objectives of Datong-to-Huangshui River Water Diversion Project, a decomposition and coordination technology of large-scale system considering the flow routing process was proposed, and a water quantity operation model for this project was constructed.Based on the coordination decomposition theory of large-scale system, the whole system of Datong-to-Huangshui River Water Diversion Project was divided into multiple subsystems, and a coordination mechanism was constructed by the hydraulic connection between the subsystems to obtain the operation scheme information of various water conservancy facilities.Combined with the one-dimensional hydrodynamic model, the key information of water level and flow of each node and section was captured.The results show that compared with the operation scheme obtained by the water allocation model, the scheme obtained by this model can not only meet the water supply demand, but also realize the dynamic tracking and simulation of the water supply process.The model can provide users with more accurate and scientific methods for preparing the water supply operation plans, and further ensure the safety of water supply along the line.