Objective To investigate the intervention effect of GDC-0449, a hedgehog signaling pathway inhibitor, on rats with liver fibrosis induced by carbon tetrachloride (CCl 4 ) combined with 2-acetylaminofluorene (2-AAF). Methods A total of 18 female Fisher344 rats were randomly divided into normal group, CCl 4 /2-AAF group, and GDC-0449 group, with 6 rats in each group. The rats in the CCl 4 /2-AAF group and the GDC-0449 group were given subcutaneously injected 30% CCl 4 -olive oil solution at a dose of 2 mL/kg twice a week for 6 weeks to induce liver fibrosis; since week 7, in addition to the injection of CCl 4 -olive oil solution, the rats in these two groups were given 2-AAF (100 mg/kg/d) by gavage, and the rats in the GDC-0449 group were given GDC-0449 (25 mg/kg/d) by gavage, while those in the normal group were given an equal volume of olive oil solution by injection and normal saline by gavage. All rats were sacrificed at the end of week 9, and related samples were collected. HE staining and sirius red (SR) staining were used to observe the changes in liver histopathology and collagen deposition, and the semi-quantitative analysis of SR-positive area and Ishak score were used to evaluate fibrosis degree; the alkaline hydrolysis method was used to measure the level of hydroxyproline (Hyp) in liver tissue; immunohistochemistry, Western blot, and qRT-PCR were used to measure the expression of α-smooth muscle actin (α-SMA), type Ⅰ collagen (Col-Ⅰ), type Ⅳ collagen (Col-Ⅳ), cytokeratin 19 (CK19), cytokeratin 7 (CK7), the epithelial cell adhesion molecule Epcam, and the hedgehog signaling pathway in liver tissue; double immunofluorescence staining was used to observe the colocalization of CK19 and the oval cell marker OV6. A one-way analysis of variance was used for comparison of continuous data between multiple groups, and the least significant difference t -test was used for further comparison between two groups. Results Compared with the normal group, the CCl 4 /2-AAF group had marked inflammatory cell aggregation and collagen deposition in liver tissue, with the formation of a pseudolobular structure, as well as significant increases in Hyp level and collagen positive area ratio in liver tissue ( P < 0.05), Ishak score ( P < 0.05), and the expression of α-SMA, Col-Ⅰ, Col-Ⅳ, Epcam, CK19, CK7, the transmembrane transporter Smoothened (Smo), Hedgehog ligand Desert Hedgehog (Dhh), the Indian Hedgehog membrane-binding receptor Patched (Ptch2), and glioma-related oncogenes Gli1, Gli2, and Gli3 (all P < 0.05); double immunofluorescence staining showed that CK19-positive cells also expressed OV6 in the liver tissue of rats in the CCl 4 /2-AAF group, with a significant increase compared with the normal group. Compared with the CCl 4 /2-AAF group, the GDC-0449 group had significant reductions in inflammatory cell aggregation and collagen deposition in liver tissue, Hyp level and collagen positive area ratio in liver tissue ( P < 0.05), Ishak score ( P < 0.05), and the expression of α-SMA, Epcam, CK19, CK7, Smo, Ptch2, Gli1, Gli2, and Gli3 (all P < 0.05); double immunofluorescence staining showed a significant reduction in the number of cells with co-expression of OV6 and CK19 in liver tissue. Conclusion The Hedgehog signaling pathway inhibitor GDC-0449 can significantly inhibit the progression of liver fibrosis induced by CCl 4 /2-AAF in rats, possibly by inhibiting hepatic stellate cell activation, collagen deposition, activation and proliferation of hepatic progenitor cells, and differentiation of hepatic progenitor cells into biliary epithelial cells.