Taking a river comprehensive improvement project as an example,three-dimensional numerical simulation of multistage fall hydraulic characteristics was carried out,using computational fluid dynamics software combined with RNG k-ε turbulence model and VOF method.The flow patterns and velocity of hydraulic drops and stilling basin were obtained,and the energy dissipation rates were calculated.The numerical simulation show the variation law of flow patterns and velocity in the river,and the research results verify the engineering design scheme and provide technical support for the engineering design.