Objective To explore the application of magnetic resonance imaging (MRI) diffusion-weighted imaging with background suppression (DWIBS) and positron emission tomography/X-ray computed tomography (PET/CT) in the staging diagnosis of lymphoma. Methods The clinical data of 50 patients with lymphoma admitted to our hospital from February 2017 to February 2018 were retrospectively analyzed. All patients were diagnosed by pathological biopsy, and they were given DWIBS and 18 fluoro-fluorodeoxyglucose (18F-FDG) PET/CT respectively. The lesions detection was compared by two methods. According to the Ann Arbor staging criteria of lymphoma, the lymphoma staging diagnosis was made by the two imaging methods, and their coincidence with clinical stages was observed. Results There were significant differences between DWIBS and PET/CT in total detected lesions and detection of intranodal lesions (P<0.05), but the results of the two methods were strongly consistent (к=0.842, 0.875). There was no significant difference in the detection of extranodal lesions between the two methods (P>0.05), but they were moderatelyconsistent (k=0.671). The coincidence rates of DWIBS and PET/CT staging with clinical stage were 80.00% (40/50) and 92.00% (46/50) respectively (P>0.05). Conclusion DWIBS and PET/CT have highconsistency in the lesionsdetection of lymphoma, and have high accuracy for staging diagnosis, and the difference between the two is not significant.