Abstract: Abstract: In order to explore the mechanisms of urea inhibition on methane explosion, we use Gaussian 09 software with density functional theory (DFT)' B3LYP6-31G** calculation method, to study the key element reactions of urea inhibition on methane explosion, to look for the transition states，to optimize the structures of reactions,transition states and products, to find out the reaction paths of the thermal decomposition of urea and the mechanisms of NH3·and HNCO· inhibition of methane explosion. It is concluded that the reaction barrier thermal decomposition of urea is 48.73 kcal/mol, the reaction could occur easily; the NH3· and HNCO· could consume the O2 and OH· radicals obviously，which bring good effects to the inhibition of methane explosion. The results could bring some support for the methane inhibition mechanism study.

Key words: Key words: methane explosion, Gaussian simulation, urea, free radical, explosion suppression mechanism