Abstract: The metro bridge is close to the Tianyuanzhonglu road bridge,and has two main double wall piers.The backwater of bridge piers is related with piers′ shape,size,configuration,river flow and so on.Empirical formulas for backwater are not universal.A distorted physical model with a scale of 1100 horizontally and 150 vertically is built for the study.This test studies the backwater,flow velocity,water surface curve and flow pattern near the bridges.The results show that water surface profile can be divided into three sections.The maximum backwater level is 0.02 m,and the length of backwater is 500 m in the upper reaches of the bridge.The maximum increase of flow velocity between piers is 0.29 m/s.