OBJECTIVE：To st udy the inhibitory mechanism of pomegranate peel polyphenols （PPP）on the proliferation of human prostate cancer PC 3 cells based on autophagy and apoptosis pathway. METHODS ：CCK-8 assay was used to investigate the effects of PPP with different concentrations （25-300 μg/mL）on PC 3 cell activity after culturing for 24，48，72 h，so as to screen the drug concentration and treatment time. PC 3 cells were divided into control group （complete culture medium ），PPP low- ，medium- and high-concentration groups. After treated for 48 h，flow cytometry and Annexin V-FITC/PI staining were used to detect cell cycle distribution and apoptosis of PC 3 cells. Western blotting assay was used to detect the expression of apoptosis-related protein as Bax ，Bcl-2，as well as the expression of autophagy-related proteins as LC 3，Beclin-1，p62，Atg12 and Atg 16. RESULTS ：The culturing time was chosen as 48 h. IC 50 of PPP was 110 μg/mL，and 50，100，200 μg/mL were chosen as low，medium，high concentrations of PPP. Compared with control group ，the percentage of PC 3 cells at phase G 0/G1 decreased significantly in PPP low- and medium-concentration groups while increased significantly at phase S ；that of PC 3 cells at phase G 0/G1 increased significantly in PPP high-concentration group ； while that of PC 3 cells at phase G 2/M decreased significantly in PPP medium- and high-concentration groups （P＜0.05 or P＜0.01）. The apoptosis rate of PC 3 cells was increased significantly in PPP groups （P＜ 0.05 or P＜0.01）. Compared with control group ，protein expression of anti-apoptosis protein Bcl- 2 and autophagy-related promoting protein p 62 were decreased in PPP groups to different extents ，while protein expression of promoting-apoptosis protein Bax as wells as autophagy-related protein LC 3-Ⅱ/LC3-Ⅰ ration and protein expression of Beclin- 1，Atg5，Atg12 and Atg 16 were increased to different extents ；there was statistical significance in above indexes in PPP high-concentration group and some of above indexes in PPP low- and medium-concentration groups （P＜0.05 or P＜0.01）. CONCLUSIONS ：PPP can inhibit the proliferation of human prostate cancer PC 3 cells，mechanism of which may be related to inducing autophagy and promoting apoptosis.