In order to verify the flow capacity of the spillway with the twisted flip bucket of the Nuomuhong Reservoir, the rationality of the building size and layout, and the rationality of the downstream energy dissipation and anti-scour design, a hydraulic model test with a scale of 1:50 was carried out. The model test was used to observe the water flow state of the twisted flip bucket spillway under the main characteristic flood level, and to measure the discharge volume, main characteristic cross-section flow velocity, dynamic water pressure, hydraulic characteristics of the outlet sill and the scouring of the downstream channel. After analysis, the design scheme of the drainage structure was basically reasonable, but there existed some problems. For instance, the water depth at the bucket was high on the left and low on the right, and the water tongue smashed to the right side of the downstream channel after the overhang. The flow velocity of each section of the downstream channel was large, and the outlet of the channel backwash occured. Aiming at the hydraulic problems in the test, a modification and optimization test was carried out on the outlet the twisted flip bucket type building. The revised plan gradually thickened the right side wall of the sill and attached a flat triangle. After the revision, the flow pattern was successfully improved. The water tongue had fallen into the middle of the channel, reducing the impact of the water tongue on the channel and the right slope of the channel. The flow velocity in the channel was reduced and the downstream washout was reduced.
