Abstract: OBJECTIVE To investigate the protective effect of the activated carbon N-acetylcysteine microcapsule (ACNAC) on liver fibrosis in rats. METHODS The model of the liver fibrosis on SD rats was constructed by dimethylnitrosamine, and the model rats were treated by ACNAC gavage with a daily dose of 20, 40, and 80 mg·kg^-1, all the rats were sacrificed after 8 weeks, and the contents of ALT, AST in serum and TGF-β₁ in hepatic tissue were detected. RESULTS Pathology results showed that the liver fibrosis model was at the stage of Ⅲ-Ⅳ, compared to the model group, the contents of ALT, AST in plasma were improved significantly and the expression of TGF-β₁ in hepatic tissue was drastically suppressed, especially in the high dose of ACNAC. CONCLUSION ACNAC has a better therapeutic effect on rats liver fibrosis compared to N-acetylcysteine and silymarinⅠ.