There are many factors which affect the removal rate of nitrogen oxides and sulfur oxides in the reactor energized by dielectric barrier discharge （DBD），such as oxygen content，relative humidity and SO2 initial concentration in the flue gas.In this paper，SO2 initial concentration，oxygen content and relative humidity in the flue gas were changed to study the reaction mechanism of NO and SO2 in the dielectric barrier discharge plasma process.The results showed that the initial concentration of SO2 varying even in a larger range had little effect on the removal rate of NO and SO2 in the N2/SO2/NO system.Increasing the relative humidity in the N2/NO/SO2/H2O system could reduce the concentration of SO2 significantly in the flue gas，and its influence on SO2 is more obvious than that on NO.In the system of N2/NO/SO2/O2，the influence of oxygen content on the removal rate of SO2 was not obvious，but more obvious on the reaction of NO in the DBD process.Adding O2 could promote the conversion of NO into NO2 and other nitrogen oxides.On the other hand，the generation of NO was also accelerated under some circumstances.Analysis of the reaction mechanism based on the experiment demonstrated that the SO2 reaction was mainly related to the active free radicals produced in the DBD process，OH and e-aq，while the NO reaction was related to O and N.