Abstract. With the intensified requirements on ambient air quality, controlling NOx emission from sintering flue gas has become the most important priority in steel industry. Ozone oxidation denitration process has become the most closely watched sintering flue gas denitration technology. In order to investigate the influence of different operating conditions on NO oxidation in practical engineering application of ozone oxidation denitration process, an ozone oxidation system was built, and sintering flue gas was extracted from the pipeline between the induced draft fan and the desulfurization tower. The influence of discharge power and O2 flow rate of ozone generator on O3 concentration, O3 yield and NO oxidation efficiency were investigated. The results indicated that NO oxidation efficiency increased with the discharge power. And the increase of O3 dosage imposed a significant influence on NO oxidation efficiency. However, little effect of O2 flow rate on NO oxidation efficiency was observed.