The safety of river piers depends on the stability of the bridge structure and the impact of river erosion. The numerical model can be used to simulate the pier scouring in different situations so that the stability and local scour of pier can be well evaluated and predicted. In this study, the Zhongsha bridge in Zhuoshui river, which simulate different flood conditions with hydraulic and sediment models, the water level, the flow velocity and the scouring and silting results in each case can be obtained, and showing the scouring and silting characteristics of the riverbed between each of the structures and bridge piers. Based on the simulation results can analysis the allowable erosion depth, the relation between erosion depth and water level of the Zhongsha bridge pier. Finally, the water level of the bridge closure is establishment according to the above two results.