Primary central nervous system lymphoma is a rare malignant tumor, and its incidence has increased significantly in recent years, accounting for about 6.6% of primary brain tumors and has taken the fifth place among intracranial tumors. The clinical manifestations of primary CNS lymphoma are mainly increased intracranial pressure (headache, dizziness, nausea, vomiting) and symptoms of neurological damage. A few patients may have intraocular lymphoma, and the main clinical manifestation is mosquito flying. 2008, an article published by a famous 3-A hospital in China, the average survival of primary CNS lymphoma with surgery plus radiation therapy supplemented with chemotherapy is 13.6 months, similar to glioblastoma, and the prognosis is very poor. If malignant lymphoma is suspected, stereotactic biopsy will be performed to determine the diagnosis. Please note that adrenocorticotropic hormones such as dexamethasone and prednisone should not be used 2 weeks before biopsy, and other relevant tests should be completed to exclude intracranial metastasis from peripheral lymphoma. 2.Treatment At present, there is no unified treatment plan in the international arena. Most of the international treatment adopts chemotherapy followed by radiotherapy, while domestic medical institutions have their own views on treatment, but the high-dose methotrexate-based chemotherapy plan is one of the most effective plans at present. Our team’s main treatment for primary CNS lymphoma is chemotherapy, and our chemotherapy regimen is methotrexate-based chemotherapy. The complete remission rate of our patients treated with systemic chemotherapy is close to 70%, which is a leading level in the international arena. These patients have complete tumor disappearance after chemotherapy and can do chemotherapy only, avoiding the huge side effects of whole brain radiotherapy; especially the incidence of radioactive leukoencephalopathy in the elderly is over 70%. Radioactive white matter encephalopathy often presents with severe brain function decline a few months after the end of radiotherapy, with a significant decrease in quality of life, and many patients cannot take care of themselves. We have the highest number of cases of this disease in the country and have successfully treated a large number of primary CNS lymphomas with high quality of life and long survival of patients. The median overall survival of our treated patients has reached 69 months, with continued follow-up. To guide the standardized treatment in China we have written the “Standardized and Standardized Diagnosis and Treatment of Malignant Tumors of the Nervous System Series” (Primary CNS Lymphoma Booklet). This can significantly improve the quality of life of patients. Although we have made some achievements in the treatment of primary CNS lymphoma, it is still our goal to explore the best treatment options for the domestic population.