Abstract： Objective： To observe the clinical effect of Xiakucao capsules in the adjuvant treatment of Hashimoto's thyroiditis. Methods：A total of 62 patients with Hashimoto's thyroiditis were selected and divided into the control group and the observation group according to random number table method，31 cases in each group. The control group was treated with levothyroxine sodium tablets，and the observation group was additionally given Xiakucao capsules based on the treatment of the control group. Before and after treatment， the changes in levels of thyroid antibody indexes including thyroglobulin antibody(TG- Ab)， thyroid peroxidase antibody(TPO- Ab)， thyroid hormone indexes including free thyroxine T3(FT3)， free thyroxine T4(FT4)，thyroid- stimulating hormone(TSH)，serum cytokines including interleukin- 1(IL- 1)，interleukin- 6(IL- 6) and tumor necrosis factor- α(TNF- α) were compared in the two groups；the incidence of adverse reactions in both groups was observed. Results：Before treatment，there was no significant difference in the comparison of the levels of TG-Ab and TPO- Ab between the two groups(P＞0.05). After treatment， the levels of TG- Ab and TPO- Ab in the two groups were decreased when compared with those before treatment，and the above two levels in the observation group were lower than those in the control group，differences being significant(P＜0.05). Before treatment，there was no significant difference in the comparison of the levels of FT3，FT4 and TSH between the two groups(P＞0.05). After treatment，the levels of FT3 and FT4 in both groups were increased when compared with those before treatment，while the TSH levels were decreased；the levels of FT3 and FT4 in the observation group were higher than those in the control group，while the TSH level was lower， differences being significant(P＜0.05). Before treatment，there was no significant difference in the comparison of the levels of IL- 1， IL- 6 and TNF- α between the two groups(P＞0.05). After treatment， the levels of IL- 1， IL- 6 and TNF- α were decreased when compared with those before treatment，and the above three levels in the observation group were lower than those in the control group， differences being significant(P＜0.05). Conclusion： In the adjuvant treatment of Hashimoto's thyroiditis， Xiakucao capsules can reduce levels of TG- Ab， TPO- Ab and TSH， increase levels of FT3 and FT4， and effectively reduce serum cytokines，with great safety.