The sudden flow in curved channel has special shock wave phenomenon and its flow pattern is very complicated,which adds difficulties to research the influence of curved channel on sudden flow and to propose improved measure .Taking the spillway of practical project for example, by use of Flow-3D software, the paper conducted three-dimensional numerical simulation for flow in bend section of steep slope based on RNG k-ε turbulence flow model and VOF method.The data of physical model test has proved the accuracy of three-dimensional numerical simulation.It anzlyzed the influence of steep slope bend on water flow regime,and presented the optimal scheme of guide-flow-wall at section of curve spillway.The result manifests that the method of guide-flow-wall can effectively improve the flow pattern in bent of sudden flow.It is feasible to conduct three-dimensional numerical simulation to bend flow.