The dielectric barrier discharge synergy with 10 wt% MnOx/TiO2–MWCNTs was investigated with different proportions of support materials. All as-prepared catalysts were analyzed by BET, ICP-AES, SEM, XRD, XPS, Raman spectroscopy and H2-TPR. The MnOx/TiO2–MWCNT (1:4) catalysts exhibited the best catalytic activity with NO removal efficiency of 72.4% at the discharge power of 45 W when temperature was ambient. This was a result of the extremely dominant phase of MnO2 (76.21%), the high concentration of lattice oxygen (74.92%) and the good dispersion of manganese oxides on the surface of the catalysts, as proven by the characterization methods used in this study. Our XPS and ICP-AES analysis illustrated that manganese oxide particles could be decorated on the internal channels of MWCNTs, which was found to be abundant with the increasing MWCNTs and exhibited better ability to adsorb NO and supply oxygen. According to the sulfur poisoning experiment, a small amount of SO2 (the concentrations of SO2 and NH3 were 1000 and 500 ppm, respectively) could facilitate the SCR catalytic performance by generating sulfate species on the surface of the carbon, which was regarded as a Bronsted acid site on the surface of the catalyst.