Abstract: PUREX process was the only commercialized hydrometallurgy reprocessing process, which could recycle the uranium and plutonium in spent nuclear fuel successfully. Pu(Ⅲ) should be oxidized to Pu(Ⅳ) before it was extracted into TBP-diluent in plutonium purification cycle of PUREX process. Meanwhile, the reductants in 1BP feed, such as hydroxamine, hydrazine and U(Ⅳ) should be oxidized. Previous research showed that N₂O₄ was an excellent and salt-free oxidant to the reductants. Therefore, oxidation of the reductants by nitrous gases mentioned above were studied in glass packed column in a gas liquid concurrent flow model. The results show that the dosage of N₂O₄, the reaction time in column and reaction temperature have significant impact on the oxidation of the reductants. When the residence time of the 1BP feed in glass column is 3 min and the dosage of N₂O₄ is 1.2 times higher than that of the total reductants, more than 99.9% of reductants are oxidized, and the oxidation rate of Pu(Ⅲ) is also higher than 99.9%.