Abstract: This study was designed to investigate the effect of dihydromyricetin (DHM) on inducing apoptosis of ovarian cancer cells A2780 through endoplasmic reticulum stress (ERS) pathway and the mechanisms involved in vitro and in vivo. A2780 cells were treated with different concentrations of DHM, and the protein expression levels of glucose-regulated protein 78 (GRP78) which is related to ERS increased, apoptotic proteins C/EBP-homologous protein (CHOP), and cysteinyl aspartate specific proteinase-12 (caspase-12) elevated. After pretreatment with ERS inhibitor, 4-phenyl butyric acid (4-PBA), following the intervention with DHM, the A2780 cell viability decreased and apoptotic rate increased. All animal welfare and experimental procedures were approved by the Animal Ethics Committee of Chongqing Medical University. Intraperitoneal injection of DHM suspension into nude mice with ovarian cancer could significantly inhibit the growth of transplanted tumor in vivo, increase the protein expression levels of GRP78, CHOP, and caspase-3. Moreover, swollen and broken endoplasmic reticulum could be observed in tumor tissues, suggesting that DHM intervention induces apoptosis mediated by ERS. The results indicated that DHM could induce apoptosis of ovarian cancer cells and inhibit the growth of transplanted tumors in nude mice, which might be related to the activation of ERS pathway.