Abstract Objective: Although the application of PET/CT in lymphomas has been the focus of many studies, the relationship between fluorodeoxyglucose uptake and biological indicators is complex and still incompletely understood, and there is a significant unmet need for more insightful differential diagnosis of PET/CT among different lymphoma subtypes. In present study, the diagnostic accuracy of 18F-PET/CT was assessed in patients with primary lymphoma and the clinical application value of SUVmax was determined. Methods: The diagnostic accuracy of a total of 97 patients with initial 18F-PET/CT scans between January 2015 and February 2020 were assessed, and the SUVmax was compared according to the different pathological subtypes. The relationship between SUVmax and immunophenotype, clinical characteristics, and genetic types were estimated. Results: According to the pathological results, 10 cases were misdiagnosed by PET/CT, and the accuracy was about 90%. Statistical analysis of SUVmax did not reveal a significant difference between Hodgkin’s lymphoma (HL) and non-Hodgkin’s lymphoma (NHL) (p=0.9071). Among NHL, the average SUVmax was statistically different between diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL) (p=0.0004), FL and natural killer/T-cell lymphoma (p=0.0078), FL and peripheral T-cell lymphoma (PTCL) (p=0.0117), DLBCL and mantle cell lymphoma (MCL) (p=0.0294). In patients with DLBCL, SUVmax was correlated with the expression level of proliferation index Ki-67 (r=0.33, p=0.018), while average SUVmax shows no difference between various immunophenotype expression levels, ages, gender, skeletal invasion situations, clinical grade stages, international prognostic index (IPI) score, and different gene types (germinal center B cell-like (GCB) and non-GCB). Conclusion: 18F-PET/CT had a marked diagnostic value in patients with primary lymphoma, but some misdiagnosis was probable. The SUVmax is valuable in the differential diagnosis of different pathological types of NHL. Simultaneously, the SUVmax of patients with DLBCL correlated with Ki-67 might reflect the tumor invasiveness, thereby revealing a prognostic value.