Objective · To explore the effect of inhibiting transforming growth factor β (TGF-β) signaling pathway on the stem cell-mediated liver regeneration in mice after partial hepatectomy (PH). Methods · Eighteen C57BL/6 male mice were selected to establish the model of hepatectomy. mRNA and protein levels of the signal molecules in TGF-β pathway, as well as stem cell markers α-fetoprotein (AFP) and leucine-rich repeat-containing G-protein coupled receptor 5 (LGR5) in the liver tissues were detected before (PH0) and on the 1st (PH1), 3rd (PH3) and 7th (PH7) day after operation. Then, additional 32 mice were assigned into inhibitor group [PH+SB-431542, 10 mg/(kg·d)] and control group (PH+normal saline). The mice were sacrificed on the 1st (PH1) and 3rd (PH3) day after operation and liver remnants were obtained. Realtime-PCR, Western blotting, and immunofluorescence staining were used to detect the expressing variation of TGF-β signaling pathway, AFP and LGR5. Results · The mRNA and protein of TGF-β1, phosphorylated SMAD2 (p-SMAD2) protein, Afp mRNA, the number of AFP immune-positive cells and Lgr5 mRNA were upregulated significantly after PH, peaked at PH3 (P<0.05) and recovered to pre-operative level at PH7. Compared with control group, the above indices were all obviously inhibited in inhibitor group at PH3 (P<0.05). Conclusion · TGF-β signaling pathway may regulate the stem cell-mediated liver regeneration in mice after PH.