Abstract: In view of the large amount of water in the Yinzhuang tailings reservoir，the large amount of flood in the rainy season，and the difficulty of drainage，in order to achieve the standard that there is no water in the reservoir after the closure of the reservoir and the discharge of a flood in the reservoir does not exceed the 72 h standard，an integrated water collection facility for flood discharge and backwater is designed above the flood discharge chute and the backwater chute，and the diversion open channel is excavat⁃ ed to extract the water in the reservoir and enter the water collection facility. Through the catchment facilities，flood discharge and backwater are carried out at the same time，and the drainage in the reservoir is preferentially returned to the concentration plant for utilization，which increases the flood discharge capacity and reduces the water consumption of the concentration plant. Practice has proved that the designed flood discharge system can meet the requirements of flood control capacity and no water storage in Yinzhuang tailings reservoir after closure，and the annual benefit is 3.747 million yuan.

Key words: tailings reservoir, closure Design, drainage system