Objective:To explore the improvement effect of scutellarin(SCU)on bleomycin(BLM)-induced pulmonary fi-brosis in mice and to analyze potential action mechanism of SCU based on transforming growth factor-β1(TGF-β1)/Smads sig-naling pathways.Methods:The models of pulmonary fibrosis mice were constructed by intratracheal injection of BLM,and they were divided into blank group,SCU group,BLM group and BLM+SCU group.After 21 d of intervention,growth status,patho-logical changes of lung tissues,levels of inflammatory factors,expressions of pulmonary fibrosis markers proteins and mRNA levels of TGF-β1,Smad2,Smad3 and Smad7 in different groups were observed.Results:Compared with blank group and SCU group,scores of alveolar inflammation and pulmonary fibrosis,levels of interleukin-6(IL-6),IL-1β,tumor necrosis factor-α(TNF-α)and hydroxyproline(HYP),expressions of α-SMA,Collagen I and Fibronectin proteins in lung tissues,mRNA levels of TGF-β1 and Smad2/3/7 were increased in BLM group(P<0.05).The above indexes in BLM+SCU group were all lower than those in BLM group(P<0.05).Conclusion:SCU can improve BLM-induced pulmonary fibrosis and inflammatory response of lung tissues in mice.The improvement mechanism may be related to the down-regulation of TGF-β1/Smads pathways.