Abstract: Objective To investigate the clinical and imaging features and prognosis of orbital lymphoma so as to reduce misdiagnosis. Methods Clinical data about 25 patients with orbital lymphoma diagnosed and treated in the first medical center of Chinese PLA General Hospital (24 cases) and Peking Union Medical College Hospital (1 case) from August 2012 to October 2019,were analyzed retrospectively.The patients were treated with surgery,radiotherapy and/or chemotherapy and the clinical features and the prognosis were analyzed. Results Among the 25 cases (28 eyes),there were 17 males (68%) and 8 females (32%) with the age ranging from 31 to 84 years.The disease course ranged from 15 days to 20 years.The orbital masses in most of the patients (22 cases) was unilateral.Ocular masses (26/28) and exophthalmos (21/28) were main manifestations.Radiographic results showed orbital bone erosion and destruction in few cases.Mucosa associated lymphoid tissue (MALT) lymphoma (15/25) was the most common patholotical type,followed by diffuse large B cell lymphoma (DLBCL,6/25),NK/T cell lymphoma (NKTCL,2/25),follicular lymphoma (FL,1/25) and plasmacytoma (1/25).After local radiotherapy and/or systemic chemotherapy,4 MALT lymphoma cases (4/15)relapsed and 1 case (1/15) died;3 primary DLBCL cases (3/4) relapsed and 2 cases (2/4) died;2 NKTCL cases (2/2) died within half a year;2 cases with transformed DLBCL,one case of FL and one case of plasmacytoma did not progressed. Conclusion There are many types of orbital lymphoma.MALT lymphoma is the most common type with slow progressing and good prognosis,while diffuse large B cell lymphoma and NK / T lymphoma are aggressive with poor prognosis.