Objective:To explore whether esketamine (ESK) can inhibit the proliferation and induce apoptosis of breast cancer cells, and explore the mechanism.Methods:CCK-8 assay was used to detect the inhibitory effect of ESK on the proliferation of breast cancer cells. Annexin V/PI staining was used to detect the morphological changes of cells; Apoptosis and reactive oxygen species were detected by flow cytometry. Western blot was used to detect apoptosis and pathway expression.Results:CCK-8 experiment results proved that ESK could inhibit the proliferation of breast cancer cells in a time-dependent manner. The survival rate of MDA-MB-468 cells treated with ESK at 20 μM was (35.47±2.61) %, which was statistically different from that treated with vinorelbine at the same concentration ( P<0.05). The IC50 value of ESK on MDA-MB-468 cells was (14.54±2.12) μM. After treatment with ESK, the mitochondrial membrane potential was significantly reduced. In the protein level, the expression of Cytochrome C, Bax and Caspase-3 was up-regulated, and the expression of Bcl-2 was down regulated, which induced the mitochondrial dependent apoptosis of MDA-MB-468 cells. ESK could up regulate the level of reactive oxygen species in MDA-MB-468 cells and regulate the expression of PI3K/AKT signaling pathway. Conclusions:ESK can inhibit the proliferation and migration of breast cancer cells and induce them to play a mitochondrial dependent apoptosis. Its mechanism is achieved by up regulating the level of ROS in breast cancer cells, thereby regulating the PI3K/AKT signaling pathway, which provides a theoretical basis for the development and utilization of Aln.