Abstract: A non-thermal plasma assisted catalyst (NPAC) reactor was designed, and La0.8K0.2Mn0.5Co0.5O3 nano- catalyst was prepared by the means of citrate-gel method. The bench test was carried out to investigate the effects of NTP special energy density and temperature on NOx reduction with NPAC system. Results showed that the concentration of O2 was reduced significantly compared with the reference test under different frequencies of NTP discharge, and the maximum reduction was to 5.17%. The concentration of NO2 was increased and the concentration of NO was reduced with the increase of NTP specific energy density. NO2 and NO began to transform when the specific energy density exceeded 80J/L under the frequency of 14.0 kHz. The catalytic activity of La0.8K0.2Mn0.5Co0.5O3 catalyst began to appear in the temperature range of 280-350℃，and the concentration of NOx was reduced effectively under the treatment of NPAC system.