The aim of this study is to create a hydraulic numerical model to analyze the hydraulic transient process associated with the water delivery system of the cascade pumping stations of the Miyun Reservoir Regulation and Storage Project. Based on the characteristics of the project, which include open channels, co-dependent structures and control structures, a mathematical model of the corresponding inner boundary was established. The numerical model of transient flow was developed by combining computer simulation techniques with the one-dimensional Saint-Venant equations. This approach is suitable for the water delivery system of cascade pumping stations. This model was subsequently applied in the study area. The numerical simulation results show that the model of the hydraulic transient process yielded relatively high precision (error of less than 2 cm). The model was used to perform numerical simulations of flow regulation and emergency conditions in the water conveyance system. The study provides a practical numerical method for precisely evaluating the hydraulic transient process for the water delivery system of cascade pumping stations, basic data for the operation and optimization of the water conveyance system, and a reference for the safe operation of the Miyun Reservoir Storage Project, as well as efficient water delivery.