The treatment of brain metastasis of small cell lung cancer is divided into immunotherapy or platinum-containing double-drug chemotherapy, followed by cranial irradiation; cranial irradiation, followed by sequential immunotherapy or platinum-containing double-drug chemotherapy. 1. Patients without symptoms of intracranial hypertension (nausea, vomiting, headache, etc.): atilizumab + etoposide + carboplatin or etoposide/irinotecan + cisplatin/carboplatin double-drug chemotherapy, followed by whole brain irradiation. 2. If the patient has obvious symptoms of intracranial hypertension, such as repeated nausea, vomiting, headache, poor appetite, etc., whole brain irradiation will be carried out first, and after the symptoms are relieved significantly, atilizumab+etoposide+carboplatin or etoposide/irinotecan+cisplatin/carboplatin double-drug chemotherapy will be carried out. It should be noted that: if the diagnosis of small cell lung cancer brain metastasis, treatment and prognosis are poor, it is necessary to consult the hospital in time for comprehensive evaluation, and individualized treatment plan should be made according to the specific conditions of patients.