The lymph nodes or masses,positron emission tomography/computed tomography (PET/CT) standardized uptake values(SUV) results, whole body magnetic resonance imaging(MRI) intravoxel incoherent motion(IVIM) sequence D, D*, f values and MRI volumes of lymphoma patients were compared before and after the chemotherapy in this project prospectively to provide data for evaluating the dependency and differences of PET/CT and whole body MRI in lymphoma staging and therapeutic evaluation. Long-term therapeutic effect indexes obtained in follow-up visits of patients such as Overall Survival(OS), Progression Free Survival (PFS) etc. were used to evaluate the diagnostic sensitivity and differences of MRI and PET/CT. The research could provide a new method of nonionizing radiation iconography for physicians to give appropriate treatments and predict prognosis.