Breast cancer is the most common malignant tumor in women all over the world, which is a serious threat to women's physical and mental health. with the in-depth exploration of the molecular mechanism of tumorigenesis and metastasis, immunotherapy has gradually become a new treatment for breast cancer, among which immunocheckpoint inhibitors are widely studied, including PD-1/PD-L1 inhibitors and CTLA-4 antibodies. Single immune checkpoint inhibitors can improve the clinical outcome of breast cancer patients, but the effect is relatively small. The combination of immunocheckpoint inhibitors with chemotherapy, radiotherapy, targeted therapy, vaccines and PARP inhibitors can enhance the response of breast cancer patients to immunotherapy, but there is a lack of immune biomarkers that can accurately predict the curative effect. More and more in-depth studies are needed to explore more effective combination therapy and immune biomarkers. This article reviews the mechanism, efficacy and safety of breast cancer immune checkpoint inhibitors