Objective To investigate the effects of sodium ferulate on lung mRNA expression of TGF-β1 signal transduction molecule in rats with pulmonary fibrosis，and explore the mechanism of sodium ferulate on pulmonary fibrosis.Methods A rat model of pulmonary fibrosis was induced by intratracheal injection of bleomycin (5 mg/kg).Thirty SD rats were randomly divided into three groups (n=10 in each group)，ie.a control group，a pulmonary fibrosis model group，and a sodium ferulate group.The lung histopathology and the expression of collagen was examined by HE staining and collagen fibril staining respectively.The expressions of TGF-βRII and Smad4 mRNA in the lung tissue were detected by situ hybridization.And the expression of TGF-β1 mRNA was detected by real-time fluorescence-quantification RT-PCR.Results Collagen fibril staining indicated that the expression of pulmonary collagen in the model group was significantly higher than that in the control group and sodium ferulate group (Plt;0.001).The mRNA expressions of pulmonary TGF-β1，TGF-βRII and Smad4 were significantly higher in the model group than those in the control group (all Plt;0.01)，and were significantly lower in the sodium ferulate group than those in the model group (all Plt;0.05).Conclusions Sodium ferulate can effectively reduce pulmonary fibrosis through inhibition of the mRNA expression of TGF-β1，TGF-βRII and Smad4 in the lung tissue，thus influence the TGF-β1/Smad4 signal transduction way and inhibit the target gene activation.