Abstract：Objective：To observe the curative effect of Xiakucao Granules combined with Thiamazole Tablets for patients with toxic diffuse goiter complicated with thyroid hyperfunction，and its effect on levels of fibroblast growth factor 21 (FGF21) and thyrotropin receptor antibody (TRAb) in serum. Methods：A total of 78 cases of patients with toxic diffuse goiter complicated with thyroid hyperfunction were selected as the study subjects and randomly divided into the control group and the observation group， with 39 cases in each group. The control group was treated with Thiamazole Tablets， and the observation group was additionally treated with Xiakucao Granules based on the treatment of the control group. Clinical effects were compared between the two groups. Before and after treatment， the levels of free triiodothyronine (FT3)， free thyroxine (FT4)， thyroid- stimulating hormone (TSH)， FGF21， and TR- Ab in serum were compared between the two groups. Results：Before treatment，there was no significant difference being found in the comparison of levels of FT3，FT4 and TSH in serum between the two groups (P＞0.05). After treatment，the levels of FT3 and FT4 in serum in the two groups were decreased (P＜0.05)，and TSH levels were increased (P＜0.05)；the levels of FT3 and FT4 in the observation group were lower than those in the control group，and TSH level was higher than that in the control group (P＜0.05). Before treatment，there was no significant difference being found in the comparison of levels of FGF21 and TR- Ab in serum between the two groups (P＞0.05). After treatment， the FGF21 levels in serum in the two groups were increased (P＜0.05)， and TR- Ab levels were decreased (P＜0.05)； the FGF21 level in the observation group was higher than that in the control group (P＜0.05)， and TR- Ab level was lower than that in the control group (P＜0.05). After treatment， the total effective rate was 92.31% in the observation group， higher than that of 76.92% in the control group (P＜0.05). Conclusion： In the treatment of toxic diffuse goiter complicated with thyroid hyperfunction， Xiakucao Granules combined with Thiamazole Tablets has more advantages than Thiamazole alone in improving thyroid function，and can regulate levels of FGF21 and TR-Ab in serum，and improve clinical effect.