〔Abstract〕 Objective To investigate the mechanism of AMD3100 reversing the resistance of human hepatocellular carcinoma cells to Sorafenib by regulating carbonic anhydrase Ⅸ(CA9) and chemokine receptor 4(CXCR 4).Methods The Sorafenib resistant cell lines Huh7/Sor and HepG2/Sor were established from human hepatocellular carcinoma cells Huh7 and HepG2.The effects of Sorafenib alone or in combination with AMD3100 on the proliferation of Huh7,HepG2,Huh7/Sor, HepG2/Sor cells were detected.The difference of invasive ability between Sorafenib resistant cells and non-resistant cells, and the effect of AMD3100 on the invasive ability of hepatocellular carcinoma cells were observed.And the regulation effect of Sorafenib alone or in combination with AMD3100 on the expression of CA9 and CXCR4 proteins in Huh7,HepG2,Huh7/Sor and HepG2/Sor cells was detected.Results Compared with the Control group, AMD3100(50 μmol/L) increased the inhibitory effect of Sorafenib on the proliferation of Huh7/Sor and HepG2/Sor cells(P<0.05).Compared with Huh7 cells, the invasive ability of Sorafenib resistant Huh7/Sor cells was significantly enhanced(P<0.05),and AMD 3100(50 μmol/L) decreased the invasive ability of Huh7 and Huh7/Sor cells(P<0.05).Compared with Huh7 and HepG2 cells, the protein expression of CA9 and CXCR4 in Huh7/Sor and HepG2/Sor cells increased(P<0.05).AMD3100(50 μmol/L) down-regulated the protein expression of CA9 and CXCR4 in Huh7,HepG2,Huh7/Sor and HepG2/Sor cells(P<0.05).Conclusion AMD3100 can reduce the resistance of human hepatocellular carcinoma cells to Sorafenib by down-regulating the expression of CA9 and CXCR4,and enhance the inhibition of Sorafenib on the proliferation and invasion of human hepatocellular carcinoma cells.