Salvianolic acid B (Sal B), one of the major water-soluble compounds of Danshen (a popular Chinese herb), possesses many of the biological activities, such as antifibrogenic effect in liver and renal diseases. Transforming growth factor-β1 (TGF-β1) plays a central role in the development of pulmonary fibrosis by stimulating extracellular matrix (ECM) accumulation and activating fibroblasts. Here, we investigated the effects of Sal B on cell proliferation, collagen synthesis, endogenous TGF-β1 production, and α-smooth muscle actin (α-SMA, a marker of myofibroblasts) expression in human lung fibroblasts stimulated by TGF-β1 in vitro. The cell proliferation rates were analyzed by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide) assay. The expression of TGF-β1 and type I collagen at both the mRNA and protein levels was detected by reverse transcription polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA), and radioimmunoassay, respectively. The α-SMA expression was detected by Western blot. TGF-β1 treatment of lung fibroblasts increased cell proliferation rates, and enhanced the expression level of type I collagen, endogenous TGF-β1 production, and α-SMA expression (P < .05). The treatment with only Sal B did not affect the proliferation and differentiation of lung fibroblasts. Interestingly, Sal B was found to inhibit TGF-β1-induced cell proliferation, expression of type I collagen, endogenous TGF-β1 production, and α-SMA expression in lung fibroblasts. Moreover, the inhibitory effect of Sal B on TGF-β1-induced proliferation and differentiation in lung fibroblasts was more significant when treated with high-dose Sal B (1 μmol/L versus 10 μmol/L, P < .05). These data demonstrate that Sal B inhibits TGF-β1-induced cell proliferation and differentiation in vitro experiment.