Abstract: In order to analyze and study the microscopic inhibiting mechanism of NH3 in methane explosion process from the perspective of molecular,applying Gaussian 09 software,using the (DFT) B3LYP / 6-31G methods of density functional theory,the related primitive reaction was quantitatively analyzed. Also,the microscopic analysis of thermody-namics and kinetics was conducted. The microscopic mechanism of NH3 inhibition of methane explosion was revealed by the process of hypothesis and test preliminary. Results show that the NH3 competes with CH4 for certain key free radical OH,and key reactants O2 ,thus the key free radicals and reactants for methane oxidation are reduced to inhibit the methane explosion chain development,so as to achieve the goal of explosion suppression.