To explore the clinical efficacy of combined application of Bailing Capsule（百令胶囊）and vitamin D in the treatment of autoimmune thyroiditis in women of childbearing age，as well as the effects on serum 25（OH）D and Th1/Th2.

Ninety-four female patients with autoimmune thyroiditis of childbearing age admitted to the hospital from January 2020 to August 2022 were selected as the research subjects and randomly divided into a study group and a control group，with 47 cases in each group.The control group received thyroxine sodium tablets and vitamin D oral treatment，and the study group was combined with Bailing Capsule oral treatment on the basis of the control group.The treatment lasted for 6 months.The levels of free triiodothyronine（FT3），free thyroxine（FT4），thyroid stimulating hormone（TSH），thyroid stimulating hormone receptor antibody（TRAb），thyroid peroxidase antibody（TPO-Ab），25（OH）Dand Th1/Th2 were measured and compared in two groups at different stages.

After 6 months of treatment，the levels of FT3 and FT4 in the study group were slightly lower than those in the control group（P>0.05），and the TSH level in the study group was significantly higher than that in the control group（P<0.05）.After 3 and 6 months of treatment，there was no significant difference in TRAb or TPO-Ab in the control group（P>0.05）.After 3 months of treatment，the levels of TRAb and TPO-Ab in the study group were significantly lower than those before treatment（P<0.05）.After 6 months of treatment，the levels of TRAb and TPO-Ab in the study group were significantly lower than those before treatment and after 3 months of treatment，and both were lower than those of the control group（P<0.01）.After 6 months of treatment，the serum 25（OH）D levels in the study group were significantly higher than those before treatment and those of the control group during the same period（P<0.05）.After 6 months of treatment，the levels of interferon（INF）-γmRNA and interleukin（IL）-10 mRNA in the study group were significantly higher than those in the control group，with statistically significant differences（P<0.01）.

The combination of Bailing Capsule and vitamin D can significantly improve the serum 25（OH）D levels and autoimmune antibody titers in women with autoimmune thyroiditis of childbearing age，providing an effective adjuvant therapy for autoimmune thyroiditis patients with low vitamin D levels.