Abstract: As the main dust-generating part of the coal mine production process, the dust concentration of the coal mining face will reach more than 5000 mg/m³, which poses a serious threat to the health and safety of miners. As the main channel of dusty airflow, the high dust concentration significantly increases the risk of coal dust explosion. In this paper, the migration and sedimentation laws of dust of different particle sizes in the return air roadway of coal mines at air speed of 1.5 m/s were numerically simulated and analyzed using numerical simulation analysis software and discrete phase model, and the distribution characteristics and sedimentation efficiency of dust concentration fields before and after the automatic spray dust prefalling water curtain were studied at 4 m and 50 m away from the inlet, respectively. The simulation results show that the average concentration of dust in the return air roadway is significantly reduced after the dust-proof water curtain is turned on, and the sedimentation rate can be as high as 90%, which effectively verifies the significant effect of the water curtain on dust control.