In order to study the synergistic effect of water mist-N₂ on CH₄-air mixture explosion, the CH₄-air mixture with CH₄ concentration of 10% was chosen as the research object. The effects of different water mist diameters and different N₂ concentrations on the suppression of CH₄-air mixture explosion were investigated using a fluid dynamics software. The results show that when the diameters of water mist ranges from 30 μm to 150 μm, the water mist with a diameter of 70 μm has the optimal suppression effect on CH₄-air mixture explosion. When the diameter of water mist is 70 μm, as the N₂ concentration increases from 5% to 30%, the peak explosion pressure of the mixed gas decreases from 0.193 MPa to 0.098 MPa, and the pressure rise rate rapidly drops to zero, the explosion temperature also gradually decreases. The presence of different concentrations of N₂ in the reaction system has an impact on the explosion temperature of the mixed gas, but has no significant effect on the cooling rate. The results are of great significance for the engineering application of water mist-N₂ synergistic suppression of gas explosions.