Abstract: Objective To study the scavenging effect of Cdinduced free radicals with Na₂SeO₃.Methods To use of electron spin resonance(ESR)with the capture-agent PBN.Results The outputs of free radicals produced by the rat liver homogenate treated with CdCl₂ were significantly reduced by adding Na₂SeO₃.The free radical-scavenging coefficient was 65.5% under the condition of the experiment.The parameters of ESR have also determined that the free radical in the system was lipid peroxide free radical(LOO·).Conclusion Selenium can eliminate the oxide free radical of the body.