Abstract: In order to solve the dust diffusion problem of the belt conveyor system and obtain the optimal parameters for the airtight ventilation and dust removal design, the discrete model of air and dust turbulence was set up by taking the movable-sieve workshop of a coal preporation plant as the research background and according to the gas-solid two-phase flow theory; simulation was made on the air flow and dust movement law in the belt conveyor system by using Fluent software, and analysis was carried out on the influence of the installation position and the structural parameters of the dust suction hood upon the dust control effect of the belt conveyor system. The research results showed that trajectory of air and dust flow was basically consistent, and the trajectory of dust flow was slightly lagged; the the installation position of the dust suction hood was not affected by the speed of the belt conveyor system, but was only determined by the trajectory of the air flow and the lag distance of the dust flow; the dust suction hood was installed at the place 1.0 m to 1.5 m away from the discharge outlet, the dust suction hood was in a frustum shape of a rectangular pyramid, and the cone angle of the frustum of a square pyramid was controlled within 60° to 70° and its height within 0.4 m to 0.6 m, and the the air volume within 8 000 m³/h to 12 000 m³/h, under such conditions, the dust removal system has the best effect and the highest operation efficiency. The dust removal test by airtight ventilation at the site proved the science of the model and the reliability of the simulation results.