【Abstract】 Objective To explore the role of Treg and Th17 cells in the pathogenic mechanism of HT. Method HT patients with normal thyroid function (n=45) were were divided into untreated group (23 subjects not taking LT4) and treated group(22 subjects taking LT4). Twentyseven healthy individuals were recruited as control group. Flow cytometry was performed to detect the percentages of Treg and Th17 cells in each group. Results HT group had lower Treg and Treg/Th17 than control group(all P＜005), but there was no significant difference of Th17 between HT and control group(p=0115). Untreated group had much higher TPOAb and TgAb titer than treated group, but no significant difference was found(all P＞005). There were no significant differences of Treg,Th17 between treated and untreated group. Treated group had higher Treg/Th17 ratio than untreated group, but the difference was no significant. In HT group, there were no correlations between TPOAb, TgAb titer and Treg,Th17 and Treg/Th17 ratio. Conclusion Treg and Th17 cells should be involved in the pathogenesis of HT and thyroid function might influent Treg and Th17 cells. LT4 could lower titer of TPOAb and TGAb, but more studies should be carried out to illuminate the menchanism.