Through establishing a testing system of non-thermal plasma reactor，the effects of NO and O2 initial concentration on the conversion rate of NO in the NO/O2/N2 system have been studied , NOx and O3 concentration as a function of special energy density has been researched too. It is conformed in this study that the oxidation of NO to NO2 is the main reaction in the NO/O2/N2 system; the conversion rate of NO is reduced with the increase of NO and O2 initial concentration, which is high when special energy density is added to 450～600J/L, the O3 concentration firstly increases and then decreases with the increase of special energy density.

Key words: dielectric barrier discharge, non-thermal plasma, specific energy density, NO