Abstract: Based on the characteristics that radioactive stainless steel passivation layer is difficult to decontaminate, we simulate the stainless steel passivation behavior and change the passivation layer structure by ozone water, making decontamination easier and improving the decontamination efficiency. The results show that when 304 stainless steel is immersed in 4 mol/L passivation solution for 6 h, an average thickness of passivation layer for 26 μm can be got. When the passivation stainless steel simulation pollution samples are immersed in 7.47 mg/L ozone water for 120 min, the passivation layer can disappear. The decontamination factor of passivition stainless steel simulation pollution samples changes with of ozone water concentration and oxidation time. The decontamination factor is improved by oxidation of ozone water for 7.7 times.