The hydrogen peroxide deoxidization method was adopted to treat the remnant Ce4+ ion in the stimulant waste liquid which was generated by Ce (IV)/HNO3 decontamination technology. The distillation method was used to remove the ammonium ion in the stimulant waste liquid. By determining the nickel concentration in the waste liquid, the amount of salt in the solution corroded from the stainless steel could be calculated. The experimental results show that the remnant Ce4+ ion in the stimulant waste liquid is deoxidized completely by adding hydrogen peroxide with H2O2 and Ce4+ Mole ratio of 1:2. When the pH values are adjusted between 11.5 and 12, more than 99% amount of the ammonium ion in the stimulant waste liquid is removed by distilling 30 min. The amount of salt in the solution corroded from the 1Cr18Ni9Ti stainless steel is calculated by the nickel concentration of the waste liquid, which is between 51.2 mg/L－70.4 mg/L.Cited