Radiation-induced brain injury is a serious untoward effect of radiotherapy for malignant tumors. Patients received radiotherapy frequently occur cognitive dysfunction which seriously affects the quality of life. Although the exact mechanisms regarding radiation-induced cognitive dysfunction remain unclear, prevention strategies targeting cognitive dysfunction are increasingly applied to clinical intervention, including whole brain radiotherapy with hippocampus avoidance, stereotactic radiosurgery in patients with multiple brain metastases, and pretreatment with neuroprotective drugs such as memantine and donepezil. In addition, measures including appropriate radiotherapy management models, regular cognitive tests, and therapeutic measures at the appropriate time are critical to improve the quality of life for brain tumor patients.