Objective To enhance the separation efficiency of rice bran and broken rice in an updraft rice mill by optimizing the air duct structure and operating parameters.Methods A combined approach of CFD-DEM coupled numerical simulation and experimental verification was adopted to investigate the material separation characteristics of the updraft rice mill under different structural and operating parameters. Key parameters, including air duct width, air velocity, baffle width, and baffle spacing, were optimized through single-factor experiments and response surface methodology.Results The addition of baffles at the lower suction inlet improved the pressure and flow velocity distributions within the air duct of the updraft rice mill, significantly increasing the upward suction rate of rice bran and reducing the settling rate of broken rice. The experimental and simulation results showed consistent trends. Response surface analysis showed that the optimal parameter combination was an air duct width of 39.2 mm, air velocity of 9.3 m/s, baffle width of 13.2 mm, and baffle spacing of 26.7 mm. Under the optimal conditions, numerical simulation verified that the upward suction rate of rice bran reached 96.2%, while the settling rate of broken rice reached 97.4%.Conclusion Through the coordinated design of flow field regulation and structural optimization, the common problem of insufficient particle separation efficiency in updraft rice mills can be effectively addressed.