Abstract: Decontamination process using Ce（Ⅳ） is a general term of technique applying one strong oxidizing agent (Ce（Ⅳ）) to decontamination, which is of high efficiency to decontaminate metals polluted by radionuclide. The liquid waste contains Ce （Ⅳ）, which has the potential risk of corroding equipment, releases NH₃ to endanger environment and human health, and the organics in which affect the following treatment process, and so on. This primary study is on safety  and treatment of liquid waste from decontamination, in connection with such decontamination process as Ce(Ⅳ)/HNO₃, oxidizing gels, oxidizing foam. The result shows Ce（Ⅳ） remains can be eliminated by reduction method, problem of NH₃ release can be solved by heating, and organics can be decomposed by ozone oxidation method, so as to make liquid waste more safe.