Abstract: A hydroproject is located at the lower reaches of the Xunjiang River, the main stream of the Xijiang River system, of which the dam axis crosses two islands and three channels, with diversion in three phases, and three times of the river closure cutting off the natural channel in the river, and the river flow flowing through the outer river sluice. An average discharge of the return period of once in 5 years is taken as the discharge standard of the middle river closure at the third stage, the corresponding design discharge for river closure is 2 030 m3/s. When implementing river closure, because the removal of the outer river upstream cofferdam is not in place and there is a disturbance caused by the guide facilities for ship lock navigation, the actual river diversion capacity of the outer river is far smaller than the design expectations, but is also influenced by water transfer requirements of the Pearl River with supplementing freshwater to suppress salty water, and controlling the flow of not less than 1 800 m3/s. The advancing speed of the river closure is limited, and the river closure time lasts longer. 2 m-thick cover layer on the riverbed is washed away, the advancing front on the right side is scoured, the reinforcing cage for protecting slope toe is collapsed, the advancing front of the reinforcing cage goes down, and cracks on the berm top appear. Too slow river closure results in falling water in the downstream of the middle river, and the downstream of the closure gap water level is lower than the design downstream water level by 2 m. And the final fall along the closure gap is twice more than the design fall, reaching 4.09 m, and construction difficulties and risks are finally increasing. A detailed analysis of river closure difficulties is made in this paper, and the solution measures are presented. The summation of the experience of the ultimate success for the river closure can provide a reference for future similar projects in the planning and implementation of the river closure.