With the increasing understanding of the unique tumor microenvironment in the brain, immunotherapy have emerged as a new and promising treatment for brain metastases. Radiotherapy and immunotherapy have a synergistic effect, and it is of great value to understand its mechanism in the treatment of breast cancer brain metastases. At present, the study of immune checkpoint inhibitors combined with radiotherapy in breast cancer brain metastases is being actively carried out, bringing new hope to patients with breast cancer brain metastases.