Compared with the general spillway, the open spillway with a wide single chute is prone to complicated flow pattern and poor aeration effect. Taking the Baleh Hydropower Project in Malaysia as an example, this study uses the VOF method and the RNG k-ε
two-equation turbulence model to carry out a three-dimensional numerical simulation of the spillway flow field. The calculation and analysis of the distribution law of the hydraulic characteristics of the spillway were made under different working conditions, such as flow pattern, velocity, and pressure along the way. At the same time, a 1∶50 physical model test was carried out. After comparative analysis, the model test results were basically consistent with the numerical simulation results, which verified the accuracy and feasibility of the numerical simulation of the hydraulic characteristics of the spillway with an open-wide single chute. Then the turbulence model was used to calculate and analyze the optimized layout of the spillway aeration sill in detail. The results show that: after the 1# aeration sill is raised by 20 cm, the length of the aeration cavity behind the sill increases from 11.03 m to 19.84 m, Energy dissipation rate increased by 6.11%; after 3# aeration sill moves up 15 m along the steep slope of the chute, the impact position of the tipping water tongue moves upward, reducing the impact on the flow pattern of the tipping nose sill section. The research results have a certain reference for the optimization design of similar projects.