The side effects of radiotherapy for brain metastases have different manifestations depending on the radiotherapy modality, as follows: 1. The side effects are relatively mild with stereotactic radiotherapy or gamma knife radiotherapy, such as the tumor near the optic nerve will have an impact on vision, and near the temporal parietal lobe will have corresponding symptoms; 2. The side effects of whole brain radiotherapy are mainly alopecia and increased intracranial pressure, which can aggravate the appearance of cerebral edema; 3. Radiotherapy will have an impact on the patient’s The side effects of radiotherapy are mainly alopecia and high cranial pressure. Overall, radiotherapy has no significant impact on the daily life of most patients.