In order to develop efficient suppression techniques and isolation materials for gas explosion, it is greatly vital to understand the intrinsic mechanism of gas explosion at atomic level. The methane explosion process was systematically explored by reactive force field molecular dynamics (MD) simulation and density function theory (DFT) calculations. The results show that the initiation step of the gas explosion process is mainly induced by center dot OH free radical, and the chain transfer process is primarily carried by the conversion from center dot HO2 to center dot OH radical. The number of free radicals, such as center dot CH3, center dot HO2 and center dot OH, greatly affect the reaction velocity during the gas explosion process. These results not only identify the critical reaction intermediates and main radical carriers of methane explosion process, but also they will provide significant theoretical guide for development of the novel and efficient gas explosion suppression methods and isolation materials. (C) 2014 Elsevier Ltd. All rights reserved.