Mn-Ni-Ox catalyst was prepared by the co-precipitation method. The most active catalysts were obtained with a molar Ni/ (Mn+Ni) ratio of 0.1. The results showed that over this catalyst, NO oxidation conversion reached 59% at 125°C and 50% at 150°C with a high space velocity of 35000h-1. Their surface properties were evaluated by means of scanning electron microscopy (SEM). The process of non-thermal plasma-assisted catalytic oxidation of NO under low-temperature was studied. And the NO conversion could reach 80% with the non-thermal plasma-assisting at 150°C when the input voltage was 30V. The increasing activities at low temperature（50~175°C）were more apparently higher than high temperature by plasma. And the low-temperature catalytic activity of the catalyst was increased with the increase of the input voltage.