Abstract: For exploring the influence mechanism of fine water mist system parameters on extinguishing mine belt fires, FDS was used to study the cooling characteristics and the fire extinguishing effect of fine water mist under different parameters. From the perspective of particle diameter, spray flow and nozzle spacing, the temperature change and fire extinguishing time in the roadway under fine water mist are compared and analyzed. The results show that the fire extinguishing effect is significantly affected by the system parameters. In a certain range, the fire extinguishing time decreases with the droplet particle size and decreases with the spray flow. Under the same droplet particle size and spray flow rate, the fire extinguishing time becomes larger with the increase of the nozzle spacing. Fine water mist with particle size of 100 m, nozzle flow of 8 L/min, and nozzle spacing of 1 m can quickly reduce the temperature of the fire field and effectively inhibit the spread of fire.