In order to analyze and compare the effect of constructiom of Maoyang bridge on river flood in different schemes,the paper built a 2D hydrodynamic model which took FVM of triangle mesh to resolve the model,and simulate the variations of water level and velocity and direction of this project.Result indicated that the original project plan has severe effect on the banked-up of water level,flow velocity and state.The biggest high of banked-up is 59.3 cm, and the largest increase value of flow velocity is 1.909 m/s.The improved scheme obviously reduced the adverse effects of water level,flow velocity and direction.The highest banked-up of water level is 8.8cm.The maximum increase value of flow velocity is 0.635m/s. The change ranges of both are small and can't basically threat the operating safety of the river.