Abstract: To discover the effect of CO which is produced by coal during the process of low-temperature oxidation on CH₄ explosion, the lower explosion limit of CO/CH₄/O₂/N₂ mixed gas is analyzed, and based on preset scheme, the effect of low CO concentration on CH₄ explosion is researched by numerical simulation under perfectly pre-mixed conditions in closed space. The results indicate that the increase of CO concentration reduces the possibility of methane explosion under the same condition; the raise of CO proportion strengthens explosive effect. Three most influential elementary reactions on the production of CO and NO₂ are Rxn^#155, Rxn^#156 and Rxn^#158.