Malignant lymphoma (ML) is one of the common malignant tumors in clinical practice, which is a malignant tumor originating from lymph nodes or extra-lymph node tissues or organs. ‘s lymphoma). According to the new WHO classification of lymphohematopoietic neoplasms in 2008, there are more than 40 subtypes, each with different pathomorphological, clinical, immunophenotypic and genetic characteristics, all of which are independent diseases (Disease entity). The most common type is diffuse large B-cell lymphoma (DLBCL), which accounts for about 40% of lymphoma incidence, and this chapter introduces the diagnosis and treatment strategies of DLBCL. The IPI (International prognosis index) score can be used to determine the prognosis of patients with aggressive lymphoma represented by DLBCL and guide the choice of treatment plan.