In order to effectively control dust pollutants and realize clean production in coal mines, this paper focuses on the diffusion characteristics of dust pollutants in typical coal roadways under the auxiliary ventilation system. The Euler-Euler and Euler-Lagrangian methods are used to analyze the dust particles moving with the airflow. Each dust particle is tracked, and the particle collision is considered by the hard sphere model and the direct simulation Monte Carlo method. Combined with the field measurement results, the overall motion law of dust particles is verified, and the dust distribution law under the influence of particle size is explored. Studies have shown that the backflow mainly occurs in fine particles and fine particles ( < 20 μm ), which contribute to dust suspension, and larger particles ( 40-60 μm ) mainly fall on the return air side.