Objective To investigate the clinical effect of Erzhi Chaishao Powder in the treatment of hyperthyroid liver damage. Methods A total of 68 patients who met the Chinese and Western diagnostic criteria were selected from 183 patients with hyperthyroidism and divided into control group and treatment group using a random number table, with 34 patients in each group. The patients in the control group were treated with methimazole combined with polyene phosphatidylcholine, and those in the treatment group were treated with Erzhi Chaishao Powder combined with methimazole. The course of treatment was 12 weeks for both groups. The changes in liver function ［alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL), alkaline phosphatase (ALP), and gama glutamyl transpeptidase (γ- GT)］, thyroid function ［free triiodothyronine (FT3), free thyroxine (FT4), and thyroid stimulating hormone (TSH)］, and traditional Chinese medicine (TCM) syndrome score were observed after treatment. Results Both groups had significantly reduced serum levels of ALT, AST, TBIl, ALP, and γ- GT after treatment (P<0.05), and the treatment group had significantly lower levels than the control group (P<0.05). Both groups had significantly reduced serum levels of FT3 and FT4 and a significantly increased level of TSH after treatment (P<0.05), and the treatment group had significantly better improvements in the serum levels of FT3, FT4, and TSH than the control group (P<0.05). After treatment, both groups had significantly reduced TCM syndrome scores (P<0.05), and the treatment group had a significantly lower TCM syndrome score than the control group (P<0.05). There was no significant difference in the distribution of clinical outcomes between the two groups (P<0.05). Conclusion Erzhi Chaishao Powder has a significant clinical effect in the treatment of hyperthyroid liver damage with few adverse effects.