Microwave plasma-assisted catalytic reduction of SO2 by CO was studied over four catalysts. The activities of the four catalysts under microwave plasma decreased in the order of CoO/gamma-Al2O3 >> SnO2 > copper wires > iron wires, which was consistent with the results under conventional heating. By comparing the activity of CoO/gamma-Al2O3 catalyst in the microwave plasma mode with that in the conventional mode, it is demonstrated that the temperature at which the full SO2 conversion was obtained in the microwave plasma mode was about 200 degrees C lower than that under the conventional heating mode. Moreover, an increase of space velocity had little effect on SO2 conversion and sulfur selectivity under microwave plasma; while under conventional heating mode, both SO2 conversion and sulfur selectivity significantly decreased with an increase of space velocity.