Objective The objective of this study was to investigate the effect of acidic conditions on epithelial mesenchymal transition(EMT) of HepG2 cells.Methods HepG2 cells were cultured under acidic and alkaline conditions to observe the difference of cell morphology.Wound healing assays were performed to detect the migration ability of the two groups.Matrigel invasion assays were used to detect the invasive ability of the cells.The expression of EMT-related genes at mRNA level was detected by RT-PCR.The expression level of EMT-related gene protein was detected by Western blot.Results The morphology of HepG2 cells was changed from epithelium to interstitial type under acid conditions.The migration ability of HepG2 cells under acidic condition was stronger than that of alkaline conditions.The number of HepG2 cells crossing Matrigel was higher than that of alkaline condition.The mRNA expression of Vimentin,Slug,Snail and Zeb1 related to EMT and the protein expression of Vimentin and MMP9 related to EMT in HepG2 cells were significantly higher than those under alkaline condition.Conclusion The acid conditions can induce the occurrence of EMT in HepG2 cells.