Abstract: This study aimed to investigate the protective effects of Baibu Tang on bleomycin-induced pulmonary fibrosis in mice. After intratracheally giving bleomycin(3. 5 mg/kg), mice were orally administered Baibu Tang once a day for 14 consecutive days, takingnintedanib as a positive control. The anti-fibrotic effects were assessed by the hydroxyproline level and the histopathological changes in H&E or Masson stained lung tissues. The results revealed that the lung coefficient, hydroxyproline content, inflammation and collagen deposition were increased significantly in the lung tissue of the model mice. Both ethanol and water extracts of Baibu Tang significantly improved all the pathological indexes in mice, but the effect of the ethanol extract was better than that of the water extract. Baibu Tang with Baibu(root of Stemona tuberosa)containing different components(neotuberostemonine, tuberostemonine and stemoninine, respectively)could significantly reduce hydroxyproline level and collagen deposition in the lung tissue of bleomycin-induced mice, and there was no significant difference in their activity. This result showed that the changes in the chemical composition of Stemona tuberosa(Baibu, monarch drug for Baibu Tang)have little effect on the anti-fibrosis activity of Baibu Tang, and its mechanism and material basis need further investigation.