Objective:To discuss the effects and active mechanism of gallic acid (GA) as main active compound in Ampelopsis japonica (AJ) to HepG2 cells proliferation. Method: The MTT method was used to determine restriction activity of GA to HepG2 cells proliferation after HepG2 cells were treated with different GA concentration. Hoechst dyeing method

fluorescence microscope

annexin V-FITC/PI double-labeling method and flow cytometry method were used to observe morphological structure change of apoptotic cells and to detect cell apoptosis quantitatively and qualitatively. Finally

JC-1 dyeing method was used to detect the potential change of HepG2 cells mitochondrial membrane. Result: The restriction of GA to HepG2 proliferation is effective in concentration of 12.5-200 mg·L-1. GA is concentration-dependence

and has an ability of inducing HepG2 cells apoptosis and reducing potential of mitochondria. Conclusion: GA is one of principle anti-tumor constitutes of AJ. And one of its anti-tumor mechanism is inducing cell apoptosis by reducing potential change of mitochondria.