The　NH　3　-SCR　technology,　based　on　CeO　2　-MnO　x　catalysts,　is　of　great　significance　for　NO　x　removal　at　low　temperatures.　Microwave　irradiation,　as　an　effective　heating　approach,　can　enhance　the　low-temperature　NH　3　-SCR　activity　of　catalysts.　Herein,　the　structure-activity　relationship　of　CeO　2　-MnO　x　oxides　catalysts　was　explored　under　microwave　irradiation.　The　MnO　x　catalyst　and　Ce-Mn(1:1)　mixed　oxide　catalyst　exhibited　good　low-temperature　de-NO　x　performance　in　the　microwave　field.　With　the　increase　of　microwave　irradiation　intensity　and　time,　the　structure　and　phase　composition　of　MnO　x　material　underwent　significant　changes.　CeO　2　played　a　key　role　in　maintaining　the　structural　stability　of　the　Ce-Mn(1:1)　catalyst.　In　addition,　microwave　irradiation　affected　the　redox　properties　and　acidity　of　the　catalyst,　regulating　the　catalytic　performance.　Suitable　microwave　operation　conditions　were　conducive　to　increasing　the　number　of　acidic　sites　and　enhancing　the　redox　properties,　which　improved　the　low-temperature　catalytic　activity　of　the　catalyst.