Abstract: Objective To explore the effects of different levels of iodine on activities of superoxide dismutase(SOD) and glutathione peroxidase(GSH-Px)in EA Trats' liver and bra in.Methods Female Lew is rats were chosen to make EAT model with pig thyroglobulin and divided into 4 groups randomly(control,mdel,model and excess iodine,and model and lowiodine group).The pathological changes of thyroid gland tissue were observed and thy roglobulin an tibody(TGAb),thyroid micro soma lantibody(TMAb),activities of SOD and GSH-Px in rats' liver and brain were detected 8 weeks after the treamtent.Results The lymphocytes in filtration was obse rved under lightmicro scope in model and lowiodine group.Some of thyroid fo lials were destroyed in model and excess iodine group.The main changes in rats iodine excess groups were expanding and confluence in thyroid follicle.The proliferation was the main change in rats of iodine deficiency group.Compared with that of model group,the levels of TGAb(75.00±15.44%)and TMAb(72.15±15.00%)in rats of model and lowiodine group were significantly higher(P<0.05).The activities of GSH-Px(122.01±10.34 mg·prot)and SOD (522.81±54.62 mg±prot)of rats' liver in model and low iodine group were lower than that of other groups(P<0.05). The activity of bra in GSH-Px(412.09±115.71 mg·prot)was the lowest in model and excess iodine group(P<0.05). Conclusion Iodine deficiency and iodine excess in EAT ratsmayled to progress o f the disease,and the effect of iodine deficiency seems more serious.