Objective To investigate the characteristics of cerebral glucose metabolism in the patients with non-Hodgkin’s lymphoma (NHL). Methods A retrospective analysis was carried out in 95 patients with freshly diagnosed and untreated NHL and 60 healthy volunteers in our hospital from January 2015 to May 2016. The results of cerebral ¹⁸F-fluorodeoxyglucose positron emission computerized tomography and computer tomography (¹⁸F-FDG PET/CT scanning) were collected. Statistical parametric mapping (SPM) was performed under a certain significance level (P<0.001) and voxel threshold (K=125 voxel) for the changes of cerebral glucose metabolism and distribution in the healthy volunteers, and the NHL patients (14 patients over 60 years old, and 81 younger than 60 years). Results Compared with control group, increased glucose metabolism was not found in NHL patients. NHL patients showed the decreased glucose metabolism in the bilateral occipital lobes, left inferior frontal gyri, and bilateral precentral gyri. The area with decreased glucose metabolism was more extensive in the left brain than in the right brain. Compared with NHL patients aged ≤ 60 years, patients aged > 60 years had both increased and decreased glucose metabolism in the brain, with decreased glucose metabolism mainly in bilateral frontal lobe and increased glucose metabolism mainly in the bilateral cerebellum. Conclusion Patients with NHL could exhibit decreased glucose metabolism, which is not distributed in the whole brain, but regionally. The involved brain regions may be related to the mental and affective functions and changes of immune function. The decreased glucose metabolism is distributed more extensively in the NHL patients over 60 years, which might be associated with the aging changes in the brain.