【Abstract】 Objective To investigate the clinical characteristics of the primary diffuse large B cell lymphoma in central nervous system and the measures of diagnosis and treatment.Methods A retrospective analysis of the clinical date of two cases with the primary diffuse large B cell lymphoma in central nervous system confirmed by pathological and immunohistochemical examination, treated in department of oncology in the first people's hospital of qujing from January 2015 to January 2017 was performed. One case were given surgery subtotal resection, postoperative treatment of the chemotherapy combined with tineposide, vincristine and cyclophosphamide combined with whole brain radiotherapy; In the other case, the tumor was not completely resected, postoperative treatment of the chemotherapy combined with high dose methotrexate and cytarabine combined with total brain radiotherapy. Thhe therapeutic efficacy of different treatment plan was evaluated.Results As of July 30, 2017, one case died from tumor progression, the other case survived and no delayed neurotoxicity was found during followup. Conclusion High dose methotrexate chemotherapy is the standard treatment of primary central nervous system lymphoma, whole brain radiation therapy can be used as a save treatment in tumor recurrence of young/ refractory patients , but the treatment of primary central nervous system lymphoma in tumor recurrence/ refractory patients remains to be further research.