Abstract: Primary intraocular lymphoma (PIOL) is a rare non-Hodgkin lymphoma and classified as a special subtype of primary central nervous system lymphoma (PCNSL). At present, the diagnosis of PIOL still faces some challenges because it can masquerade as uveitis, behcet disease and so on. Its histopathologic biopsy remains the standard approach to diagnose PIOL. Gene detection, flow cytometry analysis, and determination of cytokine levels can increase the diagnostic accuracy of PIOL. Currently, there are no standard therapies for PIOL, although local radiotherapy, intravitreal chemotherapy and high-dose systemic chemotherapy are effective to control it. However, the prognosis of PIOL is poor because it is prone to local recurrence and developing into PCNSL.Therefore, early diagnosis and treatment are very important for the prognosis of PIOL.