Objective·To investigate the effect of Astragali Radix on T lymphocyte subsets and cytokine expression in Hashimoto's thyroiditis patients with normal thyroid function.Methods·A total of 120 Hashimoto's thyroiditis patients with normal thyroid function and complete data were selected from January 2020 to December 2020 in Jinshan Branch of Shanghai Sixth People's Hospital.The patients were randomly divided into intervention group(n=60)and control group(n=60)by the method of random number table.The treatment plan of the control group was iodine appropriate state diet,and the intervention group was combined with oral Astragali Radix solution(150 mL per time,twice/d)on the basis of the treatment of the control group.The two groups were treated for 6 months.The changes in peripheral blood serum T lymphocyte subsets(CD3+,CD4+,CD8+,and CD4+/CD8+),cytokines[interleukin-2(IL-2),tumor necrosis factor-α(TNF-α),interleukin-6(IL-6),and interleukin-10(IL-10)],hypersensitive C-reactive protein(hs-CRP),erythrocyte sedimentation rate(ESR),thyroid function,autoantibody,liver and kidney function,and other biochemical indexes were compared before and after treatment between the two groups.Adverse reactions were observed during the treatment.The factors influencing the change amplitude of thyroid peroxidase antibody(TPOAb)were analyzed by multifactor linear regression.Results·Finally,118 patients,with 59 cases in each group,were included in the study.After 6 months of treatment,the intervention group showed significant improvements in the proportions of CD4+ T cells,the ratio of CD4+/CD8+,and the levels of IL-2,TNF-α,IL-10,hs-CRP,ESR,TPOAb,and thyroglobulin antibody(TGAb)compared to the values before treatment and in the control group(P<0.05).There were no statistically significant differences on the above indicators before and after treatment in the control group(P>0.05).No serious adverse reactions were observed in the intervention group.Multiple linear regression analysis results showed that the use of Astragali Radix,increase of CD4+ level,increase of CD4+/CD8+ ratio,and decrease of hs-CRP level were influencing factors for the decrease of TPOAb level(β=-0.393,P=0.029;β=-0.513,P=0.010;β=-0.351,P= 0.035;β=0.434,P=0.023).Conclusion·Astragali Radix can improve the levels of CD4+ T cells,CD4+/CD8+ratio,IL-2,TNF-α,IL-6,and IL-10 in Hashimoto's thyroiditis patients with normal thyroid function,and it is safe to use.