Abstract: OBJECTIVE: To investigate the inhibitory effect of α-lipoic acid on immune thyroiditis mice (AIT) and its effect on lymphocyte subsets. METHODS: Eighty NOD.H-2h 4 female rats were randomly divided into a control group and given double distilled water for gavage; the AIT group was given 50 mg/L sodium iodide sterile double distilled water for gavage ; Low- and high-dose α-lipoic acid intervention group was injected intraperitoneally with 0.1 and 0.4 g/L α-lipoic acid daily. Twenty animals in each group continued to intervene for 8 weeks. After 8 weeks of intervention, HE staining was used to observe lymphocyte infiltration, flow cytometry was used to detect Th17, Treg, CD4+, CD8+ T cells and CD4+/CD8+ levels, and Western-blot method was used to determine P38MAPK and NF-κB protein levels. RESULTS: The incidence of thyroid inflammation of mice in the AIT group was as high as 85%. The incidence of thyroiditis, the degree of thyroid inflammation, and the proportion of Th17 cells in the AIT + low / high-dose alpha-lipoic acid group were significantly lower than those in the AIT group (P <0.05), and the proportion of Treg, CD4+, CD8+, and CD4+/CD8+ cells were significant Higher than that in the AIT group (P <0.05). The AIT + low / high-dose α-lipoic acid group had significantly lower relative protein expression levels than those in the AIT group (P <0.05). Conclusion: α-lipoic acid can reduce the expression of inflammatory cytokines in autoimmune thyroid mice, improve the proportion of lymphocyte subsets, thereby suppressing the inflammatory response and improving the symptoms of AIT.