Abstract: The simultaneous removal of NO_x and soot was studied by the temperature program reaction (TPR) technology over La_0.8K_0.2MnO₃ catalyst assisted by plasma. When the experiment was carried out by catalysis process, the results showed that La_0.8K_0.2MnO₃ catalyst had the excellent catalytic performance for the reduction of NO_x by soot in the oxygen rich atmosphere. When the experiment was conducted by catalysis with the assistant of plasma in the same gases condition, the results showed that plasma improved the catalytic activity for simultaneous removal of NO_x and soot, and reduced the combustion temperature of soot. As a consequence, the ignition temperature of soot was reduced from 300 ℃ to 280 ℃, and the burning out temperature was also decreased from 425 ℃ to 380 ℃. The conversion efficiency of NO_x to N₂ was improved by plasma, and the selectivity to N₂ formation was enhanced from 1.12％ to 1.53％. In addition, the catalytic property for soot removal was studied at various gas compositions with or without plasma. The results also showed that plasma improved the catalytic activity for the combustion of soot and the conversion efficiency of NO_x to N₂ whether in the NO＋O₂ or NO atmosphere. Also, the mechanism of plasma-assisted catalysis for simultaneous removal of NO_x and soot was discussed in this paper.