Small cell lung cancer brain metastasis may recur after radiotherapy. Small cell lung cancer is a malignant tumor with high probability of recurrence, and it is easy to spread all over the body, so it is also easy to enter the brain and form brain metastases. For patients with headache, nausea, vomiting, or even limb movement restriction, whole brain radiation therapy can be given, and appropriate dehydrating agents, such as mannitol, can be given to reduce intracranial pressure and alleviate the symptoms. In addition to the treatment for the cranium and brain, patients also need to choose chemotherapy and targeted therapy according to their conditions. However, patients with brain metastasis belong to advanced stage cancer, and it is difficult to completely eliminate tumor cells after treatment, so it is easy to have cancer recurrence. It is recommended that patients receive standardized treatment under the guidance of doctors and undergo regular review.