Abstract: In order to study the influence of nozzle’s internal structure on dust suppression by spraying in coal mine, using Fluent software, the internal flow fields of micro-oscillating cavity nozzles with different structures were simulated by grid independence test and SIMPLEC algorithm. The simulated results show that the structure of the micro-oscillating chamber on the inner wall of the nozzle has a great influence on the outlet speed, when the inlet pressure is 8 MPa, it presents the maximum speed difference between the two nozzles; moreover, both nozzles are gradually increasing along the axial direction, resulting in maximum velocity in the throat section; the stepped inner wall micro oscillation chamber nozzle can further increase the nozzle outlet speed as compared with the regular inner micro oscillation chamber nozzle; in the lining micro oscillation cavity nozzle, the atomization is generated inside the micro-oscillating chamber and the cavity opening, furthermore, it will produce varying degrees of eddy currents in the micro-oscillating cavity.