La-Mn-O perovskite catalyst was successfully prepared by microwave irradiation processing using only several minutes for heat treatment, and characterized by XRD, SEM, XPS, H-2-TPR and O-2-TPD. The catalyst by microwave irradiation processing with 6 min, mainly non-stoichiometric excess oxygen LaMnO3.15 phase, shows excellent catalytic performance. Compared with the sample prepared by conventional method, it possesses relative higher surface area, the increase in Mn4+ and oxygen vacancy content and the enhancement in the mobility of lattice oxygen which play an important part in the methane combustion.