In view of varied terrains and the complex water system in the Lian'anwei flood protection zone, a hydrodynamic model coupling one-dimensional flow model and two-dimensional unsteady flow model was developed for flood simulation based on hydraulic methods. The model took into account the combined scenarios of hilly terrain, floods with different return periods, and weak dikes of the flood control system in the study area, and was used to simulate the submerged area, water depth, breach flow process, and flood routing process in the flood protection area under different scenarios. The results show that the model can accurately reflect impacts of floods caused by dike breaching and provide technical support for early warning of flood disasters.