Abstract: In view of narrow and bending rivers，traditional continuous flip bucket is set at the end of discharge structure，and jet stream directly hits bank slope，threatening safety of buildings，and the jet nappe is difficult to return to river smoothly.The water nappe and spatial shape of jet nappe of contorted & cut flip bucket was simulated with three-dimension through RNG k-ε turbulence model and Tru-VOF method.Research showed that large-angle shooting of bucket made jet stretch vertically，deflection of left side wall could ensure that water flow out of bucket would overturn horizontally so that water nappe was lead to right riverbed.It could adapt to changes in topographical conditions of downstream river valley，and reduce erosion of downstream river channel effectively，reduce fogging phenomenon simultaneously.Simulation results also showed that the minimum number of cavity σ near the exit of bucket was 0.60，and it was less prone to cavitation damage.