Objective: To investigate the role of hypoxia inducible factor 1α (HIF-1α) in epithelial-mesenchymal transition (EMT) process of hepatocellular carcinoma. Methods: HIF-1α inducible liver cancer cell line HepG2Tet-on-HIF-1α cells were used. First, the mRNA and protein expressions of EMT-related molecules (E-cadherin, vimentin and FSP-1) and HIF-1α in HepG2Tet-on-HIF-1α cells under hypoxia were determined by real-time PCR and Western blot analysis, respectively. Then, under normoxia condition, the expressions of above molecules were determined in HepG2Tet-on-HIF-1α cells with HIF-1α overexpression induced by doxycycline (Dox), and HepG2Tet-on-HIF-1α cells transfected with HIF-1α siRNA after Dox treatment. Results: After hypoxia treatment, the mRNA and protein expressions of EMT-related molecules and HIF-1α in HepG2Tet-on-HIF-1α cells were all significantly increased compared with normoxia status (all P<0.05). Under normoxia condition, HIF-1α was overexpressed, and the EMT-related molecules expressions were simultaneously increased significantly in HepG2Tet-on-HIF-1α by Dox exposure (all P<0.05), but the above effect of Dox was abolished by HIF-1α siRNA transfection. Conclusion: HIF-1α can promote EMT process in HepG2 cells, and probably may be an effective target for liver cancer gene therapy.