OBJECTIVE：To study the effects of loganin on the prolife ration and apoptosis of liver cancer HepG 2 cells，and to explore its mechanism. METHODS ：CCK-8 assay was used to detect the effects of different concentrations （10，25，50，100， 150，200，300，400 µg/mL）of loganin on the proliferation activity of HepG 2 cells for 24 and 48 h. HepG 2 cells were divided into control group ，loganin low-concentration ，medium-concentration and high-concentration groups （50，100，150 μ g/mL）. After treated for 24 h，morphological changes of apoptosis of cells were detected by Hoechst 33342 fluorescence staining. The apoptosis and cycle distribution of cells were detected by flow cytometry. Western blotting was used to detect protein expression of Cyclin D1， PCNA， Bcl-2， Caspase-3， Cleaved-Caspase-3， Caspase-9 and Cleaved-Caspase- 9. RESULTS ： Loganin inhibited the proliferation of HepG 2 cells，in concentration-dependent trend. Compared with control group ，apoptosis as pyknosis and fragmentation occurred ，and the apoptosis rate increased significantly in loganin low-concentration ，medium-concentration and high-concentration groups （P＜0.01）；the cell were mainly blocked in S phase ；relative protein expression of Cyclin D 1，PCNA and Caspase- 3 were significantly decreased ，while that of Cleaved-Caspase- 3 were significantly increased in loganin low- concentration， medium-concentration and high-concentration groups （P＜0.05 or P＜0.01）； relative protein expression of Cleaved-Caspase-9 were increased significantly ，while that of Bcl- 2 and Caspase- 9 were decreased significantly in loganin medium-concentration and high-concentration groups （P＜0.05 or P＜0.01）. CONCLUSIONS ：Loganin can significantly inhibit the proliferation and induce apoptosis of HepG 2 cells，the mechanism of which may be associated with inhibiting Bcl- 2 protein expression and promoting Caspase- 3，Caspase-9 activation.