Abstract: Objective To investigate immune mechanism of autoimmune thyroid disease (AITD) caused by excessive iodine.Methods High iodine thyroid autoimmune disease model was established to detect the changes of expression level of thyroid stimulating hormone acceptor (TSHR) mRNA and the antigen-presenting function of dendritic cell (DC) based on the analysis of the changes of T3,T4,TSH,TSHRAb and thyroid pathology.Results Indications of AITD were observed among the mice with excessive iodine feeding for three months.The expression levels of TSHR mRNA,CD80,CD86-co-stimulatory molecules of DC,CD11c-the symbol of characteristic expression in DC,MHC-Ⅱmolecules-the antigen istocompatibility complex in the surface of DC were significanct higher than those of normal control group.Conclusion Excessive iodine strengthen the competitive reaction of TSHR,antigen-presenting function of DC,and leads mainly to humoral immune thyroid autoimmunity.