A process of simultaneous desulfurization and denitrification of flue gas was conducted in this study.The flue gas containing 200 mg· m-3 NO,1000-4000 mg· m-3 SO2,3％-9％ O2,and 10％-20％ CO2 was first oxidized by O3 and then absorbed by ammonia in a bubbling reactor.Increasing the ammonia concentration or the SO2 content in flue gas can promote the absorption of NOX and extend the effective absorption time.On the contrary,both increasing the absorbent temperature or the O2 content shorten the effective absorption time of NOX.The change of solution pH had substantial influence on NOX absorption.In the presence of CO2,the NOX removal efficiency reached 89.2％ when the absorbent temperature was raised to 60 ℃,and the effective absorption time can be maintained for 8 h,which attribute to the buffering effect in the absorbent.Besides,both the addition of Na2S2O3 and urea can promote the NOX removal efficiency when the absorbent temperature is 25 ℃,and the addition of Na2S2O3 had achieved better results.The advantage of adding Na2S2O3 became less evident at higher absorbent temperature and coexistence of CO2.In all experiments,SO2 removal efficiency was always above 99％,and it was basically not affected by the above factors.