Thirty rats were randomly divided into normal control group (group A), non-paederia scandens treatment model group (group B) and paederia scandens treatment model group (group C). The expression of mRNA of TGF-β1, Smad3 and Smad7 was detected by real-time quantitative fluorescence method after 8 weeks. The results showed that, according to the ELISA data of interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), the difference between group C and group A was extremely significant (P<0.01), which is the same as between group B and group A, and that the difference between group C and group B was significant (P<0.05). The difference between group B and group A was extremely significant (P<0.01). After treatment with paederia scandens, the expression of TGF-β1 mRNA was significantly inhibited, the difference between group C and group A was significant (t=2.245, P<0.05), and the difference between group C and group B was extremely significant (t=1.142, P<0.01). After treatment with Paederia scandens, the expression of Smad3 mRNA was significantly inhibited, the difference between group C and group A was significant (t=2.149, P<0.05), and the difference between group C and group B was extremely significant (t=1.206, P<0.01). Afterwards, the expression of Smad7 mRNA was increased, the difference between group C and group A was significant (t=2.201, P<0.05), and the difference was significant between group C and group B (t=1.007, P<0.01). Paederia scandens can inhibit the expression of TGF-β1 mRNA, decrease the expression of Smad3 mRNA, and increase the expression of Smad7 mRNA. It is shown in our study that in the mechanism of liver fibrosis, there exists a linear channel effect of Smad3 mRNA-(TGF-β1 mRNA)-Smad7 mRNA.