The synthesis of H2S in ovarian cancer is mainly regulated by CBS and CBS is highly expressed in both primary epithelial ovarian cancer and ovarian cancer cell lines, and down‐regulation of CBS in vitro induces oxidative stress to trigger apoptosis cascade by regulating GSH, ROS, p53, and NF‐κB in ovarian cancer cells, and reduces NAD/NADH ratio and ATP production by inhibiting mitochondrial respiration. This evidence concerns the gene CBS and ovarian carcinoma.