Abstract: Taking a swirling-cored nozzle for spraying for dust suppression in Yanzishan Mine 8204 working face as the object, the flow state of the pressure water in the nozzle and the spray diffusion law of the nozzle and the effects of the spray pressure and the flow rate on the spray dust fall efficiency were studied. Whether the swirling core is slotted or not will directly affect the spray effect of the nozzle. The swirling-cored nozzle without opening had large spray diffusion angle and good atomization effect, but the spray range was short and the demand for water quality was high. The swirling-cored nozzle with opening had larger spray range and stronger pollution resistance, but the spray diffusion angle was smaller. The larger the diameter of the nozzle is, the larger the spray diffusion angle is. The relationship between the spray nozzle diameter and the spray diffusion angle of the nozzle was established. The practice in-situ shows that the average dust fall rate of the designed spray nozzle is 68.95% to 75%, and the dust suppression efficiency is improved.