Observe the therapeutic effect of Danshensu on lung injury for rats, as well as explore the mechanism of Danshensu in TGF-beta 1/Smads signaling. Thirty Sprague-Dawley (SD) rats were intratracheally instilled with bleomycin to induce lung injury and interstitial fibrosis. Divided Thirty rats into three groups. DA group (n = 10): Inject 15 mg/kg Danshensu into the abdominal cavity; DXM group (n = 10): Inject 1 mg/kg dexamethasone into the abdominal cavity; BLM group (n = 10): Inject 2 mL physiological saline into the abdominal cavity. Then ten SD rats were intratracheally instilled with physiological saline as normal control group, NC group: Inject 2 mL physiological saline into the abdominal cavity. After a period of 28 days, the degree of pulmonary alveolitis was evaluated using hematoxylin-eosin (HE) staining, and the degree of lung fibrosis was evaluated using Masson's trichrome (MT) staining. The immunohistochemistry was used to determine the expression of alpha-SMA. Magnetic nanoparticles+ rtQ-PCR was used to determine the mRNA expressions for TGF-beta 1, Smad3, and Smad7. The alveolitis and pulmonary fibrosis in DA rats were obviously less than those in BLM rats and DXM rats. The expression of alpha-SMA in DA rats was obviously less than that of in BLM rats and DXM rats; the mRNA expression of TGF-beta 1 and Smad3 in DA rats were obviously reduced; the Smad7 mRNA expression was obviously up-regulated. DA can alleviate rat lung injury caused by bleomycin. Inhibiting the TGF-beta 1 and Smad3 mRNA expression, as well as boosting the Smad7 mRNA expression is one of the mechanisms by which Danshensu reduces lung injury.