Triple-negative breast cancer (TNBC) is the most aggressive type of breast cancers. Chemotherapy is the most important therapeutic option for TNBC, and chemotherapy-induced nausea and vomiting (CINV) is inevitable. Metoclopramide is a good and cost-effective therapeutic option for chemotherapy-induced nausea and vomiting. However, it is not commonly used in breast cancer because it can increase serum prolactin levels by blocking dopamine D2 receptor. This study aimed at elucidating the effect of metoclopramide on triple-negative breast cancer, MDA-MB-231 cells were treated with various concentrations of metoclopramide, the cell proliferation was detected by MTT method, the apoptosis rate was detected by Annexin V/PI double staining method, the expression change of death-related protein was detected by Western Blot. We found that metoclopramide inhibits cell proliferation and induces cell apoptosis of MDA-MB-231 in a concentration-dependent manner, and the Bcl family was involved in this process.