Objective To study the effects of alpinetin on apoptosis of Hep3B cells and explore the related mechanism.Methods Hep3B cells were cultured in vitro,treated with alpinetin; RT-PCR and Western blot was used to detect the mRNA and protein levels of Bcl-2; MTT assay was used to detect the cellular growth inhibitory rate; Annexin V-FITC/PI double staining was used to detect the apoptosis rate of cells; Mitochondrial membrane potential was analyzed by flow cytometry; Western blot was used to detect protein expression of Caspase-3,9 and Cytochrome C ; the experiment was carried out in four groups:control group,high dosage of alpinetin group,middle dosage of alpinetin group and low dosage of alpinetin group.Results The expression of Bcl-2 in Hep3B cells were decreased by alpinetin.After treated with different dosages of alpinetin (40,80,120 μmol/L),the apoptotic inhibitory rate detected by MTT were 6.38％ ± 1.32％,21.58％ ± 1.97％ and 43.18％ ± 3.89％,significantly higher than those in control group (tlowdose =13.01,tmiddle dose =15.12,thighdose =14.79,average P ＜ 0.01) ; the expression of mitochondrial membrane potential green fluorescence protein (GFP) were 18.93％ ± 2.3％,31.11％ ± 2.67％ and46.06％ ± 2.95％,significantly higher than those in control group (tlow dose =16.70,tmiddle dose =31.38,thigh dose =48.15,average P ＜ 0.01).Western blot analysis showed that the expression of Caspase-3,9 andCytochrome C in cytoplasm significantly was higher than those in control group(Caspase-3:llow dose =11.94,tmiddle dose =10.18,thigh dose =18.82,average P ＜0.01; Caspase-9:tlow dose =15.11,tmiddle dose =20.41,thish dose =21.25,average P ＜0.01; Cytochrome C:tlow dose =15.11,tmiddle dose =28.47,thigh dose =16.01,average P ＜ 0.01).while that Cytochrome C in mitochondria significantly lower than those in control group (tlow dose =16.70,tmiddle dose =12.00,thighdose =27.61,average P ＜ 0.01).Conclusions Alpinetin promotes apoptosis of human hepatic cancer cells Hep3B by down-regulating Bcl-2,probably through mitochondrial pathway.