In order to improve the shortage of uneven distribution of flow velocity in circular-ring desilting and sediment ejection pool,the paper used physical model to study the center outlet ring.It also carried out structure optimization to center outlet ring.Under the condition of constant guarantee ring maximum height of weir, the paper adjusted the ring weir export from flat mouth to curve type 1 and type 2.Under three kinds of flow condition (2 m3/s，3 m3/s，4 m3/s) it measured the velocity over flow weir outlet. The results show that the type curve center weir ring can make the overflow dam line nearly velocity overall decline compared with that of flat mouth ring and is more uniform. From the analysis of curve type 1 and type 2 maximum, minimum and average flow velocity contrast,it is found that the falling of curve type 2 on circular-ring desilting and sediment ejection pool is more apparent, the fall of velocity in circular -rings weir for curve type 2 is better than that for curve type 1.The test can provide a certain reference for the design of circular-ring desilting and sediment ejection pool under different flows.