Objective:To analyze the clinical features of EBV-associated Hemophagocytic lymphohistiocytosis and other EBV-related diseases to improve early diagnosis of EBV-HLH. Methods:34 cases in EBV-HLH group and 45 cases in EBV-non HLH group were enrolled for a retrospective study. Results:The prognosis of EBV-HLH was very poor with the mortality rate of 76.5% within six months after diagnosis. Compared with the EBV-non HLH group,the incidence of cytopenia,hepatic dysfunction,elevated serum ferritin,and hypofibrinogenemia in EBV-HLH group was significantly higher. Hemophagocytic phenomenon in bone marrow was discovered in 83.3% of the cases in EBV-HLH group and 26.7% in EBV-non HLH group. The sCD25 levels were detected as higher as 2 400.0 pg/ml in 100% cases and the percentage of NK cells were reduced in 81.8% of HLH patients. The result of ROC curve analysis showed that SF≥3 025 μg/L could be a predictor of the EBV-HLH cases developing into lymphoma/leukemia . Conclusion:A multiple of clinical data should be considered to make a diagnosis of EBV-HLH.sCD25 and the proportion of NK cells should be detected as early as possible of patitents with EBV infection,elevated sCD25 level and reduced NK cell percentage contribute to the diagnosis and differential diagnosis of EBV-HLH;Hemophagocytic phenomenon is an important but not a necessary indicator of HLH;Serum ferritin is a predictor of prognosis.