Water mist as an effective explosion inhibitor has wide application prospect to prevent and reduce gas explosion hazard. The quantitative study of gas explosion inhibition with water mist provides the groundwork for the design of gas explosion suppression system. In this paper, the influence of the initial droplet sizes and spraying concentrations on explosion inhibition were numerically studied in a 2D numerical model. Under the initial spraying concentrations in the range of similar to 1.5 kg/m(3), the inhibition effect of water mist on the explosion overpressure was not significant. The inhibition effect of water mist was mainly reflected in the suppression of the explosion flame temperature. When the initial droplet sizes were in the range of 50-150 mu m, the flame length was obviously reduced. But when the initial droplet sizes were less than 50 mu m or more than 150 mu m, the inhibition to reduce flame length begin to weaken. The results of this study provide the theoretical basis of the suppression technology for gas explosion.