Objective:To observe the effects of Xiaoying Mixture on thyroid autoantibodies in early Hashimoto thyroiditis (HT) in women of child-bearing potential. MethodsA randomized, double-blind, parallel-group, placebo-controlled study was conducted, in which 64 women with HT who met the inclusion criteria were assigned into treatment group and control group, 32 patients in each group. The treatment group was treated with Xiaoying Mixture and the control group was given placebo. The treatment course was 12 weeks in both groups. Titers of thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TGAb) and levels of sex hormones including follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E,2,), progesterone (P), testosterone (T) and prolactin (PRL) were measured before and after treatment. Menstruation and pregnancy were recorded in both groups.  Results:After treatment, the level of TPOAb in the treatment group was significantly lower than that before treatment (P,<,0.05), and there was statistically significant difference between the groups (P,>,0.05). Before and after treatment, there was no significant difference in the levels of TGAb, FSH, LH, E,2, P, T or PRL between the groups (P,>,0.05). Before and after treatment, there was no significant difference in abnormal menstruation between the groups (P,>,0.05). During the trial, there was no new pregnancy or adverse pregnancy outcomes in either group.  Conclusion:Xiaoying Mixture reduces the titer of thyroid autoantibodies in HT in women of child-bearing potential, but there are no significant positive results in menstruation and adverse pregnancy outcomes.