〔Abstract〕 Objective To investigate the effect of glycyrrhizin on the fibrosis of silica-treated mice. Methods C57 BL/6 male mice were randomly divided into control group, silicosis model group and glycyrrhizin treatment group, with 6 mice in each group. The pathological changes of lung tissues were observed by HE and Sirius red staining. Lung function indexes were detected by respiratory function instrument. The content of hydroxyproline in the lung tissues was detected by corresponding kit. The mRNA levels of monocyte chemotactic protein 1(MCP-1), fibronectin(FN) and alpha-smooth muscle actin(α-SMΑ) were detected by real-time fluorescent quantitative PCR.The number of leukocytes in the bronchoalveolar lavage fluid(BALF) was counted and the secretion of transforming growth factor-β1(TGF-β1) in BALF was detected by ELISA.Results HE and Sirius red staining showed that the inflammatory cells and the collagen were accumulated in the lung tissue of mice in silicosis model group. After treatment with glycyrrhizin, the accumulation of inflammatory cells and the collagen was ameliorated. Compared with the control group, pause(PAU) and enhanced pause(Penh) increased in the model group(P<0. 05). Glycyrrhizin treatment improved the respiratory function in mice. Furthermore, glycyrrhizin also effectively reduced the increase in the content of hydroxyproline, the expression of MCP-1, FN and α-SMΑ mRNA, the number of leukocytes and the secretion of TGF-β1 induced by silica treatment in mice(P<0. 05).Conclusion Glycyrrhizin can improve the pulmonary function and alleviate the fibrosis in mice with silicosis.