OBJECTIVE To investigate the anti-pulmonary fibrosis effect of linarin in vivo and in vitro， and investigate its mechanism preliminarily. METHODS C57BL/6J mice were randomly divided into normal group （carboxymethylcellulose sodium）， model group （carboxymethylcellulose sodium）， positive control group （pirfenidone， 200 mg/kg）， linarin low-dose and high-dose groups （12.5， 25 mg/kg）， with 8 mice in each group. Except for normal group， pulmonary fibrosis model was induced in other groups. After modeling， they were given relevant medicine intragastrically， once a day， for consecutive 14 d. The general situation of mice was observed， and their lung indexes were measured； the levels of tumor necrosis factor-α （TNF-α） and transforming growth factor-β1（ TGF-β1） in serum and interleukin-6 （IL-6） in lung tissue were determined. Hematoxylin-eosin （HE） staining and Masson staining were used to observe the histopathological morphology of lung. The pulmonary fibrosis was scored according to Ashcroft score standard. The expressions of α-smooth muscle actin （α-SMA） and （type Ⅰ collagen， Collagen Ⅰ）， phosphorylated extracellular signal-regulated kinase （p-ERK1/2） and TGF-β1 in lung tissues were detected. HFL1 cells were stimulated by TGF- β1 to form pulmonary fibrosis model in vitro， which were divided into normal group， model group and linarin low-， medium- and high-concentration groups （3.7， 7.4， 14.8 mg/L）. After being cultured for 48 h， the protein expressions of α-SMA， Collagen Ⅰ and p-ERK1/2 in HFL1 cells were detected. RESULTS In vivo， compared with normal group， the lung index of model group and the levels of TNF- α， TGF- β1 and IL-6 were significantly increased （P＜0.01）. There were a large number of inflammatory infiltration and cellular fibrosis lesions in the alveoli， and a large number of collagen depositions. The scores of HE staining and Masson staining were significantly increased （P＜0.01）. The protein expressions of α-SMA， Collagen Ⅰ， p-ERK1/2 and TGF-β1 in lung tissue were up-regulated significantly （P＜0.01）. Compared with model group， above indexes of mice were improved significantly in linarin high-dose group （P＜0.05 or P＜0.01）， and most of indexes （except for lung index） were improved significantly in linarin low-dose group （P＜0.05 or P＜0.01）. In vitro， compared with blank group， the density of cells in the model group increased， and obvious proliferation and other changes occurred； protein expressions of α-SMA， Collagen Ⅰ and p-ERK1/2 were significantly up-regulated （P＜0.05 or P＜0.01）. Compared with model group， the cell density of each concentration group was decreased and the morphology gradually returned to normal； the expressions of above proteins in linarin high-concentration group and the protein expression of p-ERK1/2 in linarin medium-concentration group were down-regulated significantly（P＜0.05 or P＜0.01）. CONCLUSIONS Linarin may regulate ERK and inflammatory pathways to reduce the inflammatory response， thereby exerting anti-pulmonary fibrosis effect.