In order to explore the influence of water on the chain reaction characteristics of gas explosion, the 20 L explosion ball experiment and the homogeneous constant volume combustion reactor of CHEMKIN 17.0 simulations were carried out. The gas explosion response under four different water contents was tested and simulated. The effects of water on the pressure, free radicals, and reactants of gas explosion were compared and analyzed. The research results show that the inhibition of water on gas explosion was enhanced with the increase of water fraction in the initial mixture; the temperature, pressure, catastrophic gases such as CO, and concentration of activation centers in the reaction system can be reduced by water; the intensity of gas explosion can be reduced by inhibiting the formation of H, O, and OH free radicals, the main reactants of gas explosion and gas explosion energy.