Inclusion Criteria:  Untreated CD20-positive DLBCL confirmed. 18 years to 75 years; Male or female patients. IPI score of 1 to 2 and an ECOG performance status of 0 to 2. More than 6 months life expectancy. At least one measurable lymph node: For intranodal lesions, equal or greater than 1.5 cm in the long axis and equal or greater than 1.0 cm in the short diameter; For extranodal lesions, equal or greater than 1.0 cm in the long axis. Adequate cardiac function (LVEF≥50%). Absolute neutrophil count(ANC) ≥1.5*109/L and platelet count(PLT) ≥75*109/L and hemoglobin ≥75g/L, total bilirubin level ≤1.5×upper limit of normal (ULN), aspartic acid Aminotransferase (AST), alanine aminotransferase (ALT)≤2.5×ULN, creatinine level (Cr)≤1.5×ULN. Signed an informed consent form which was approved by the institutional review board of the respective medical center.  Exclusion Criteria  Primary central nervous system(CNS) lymphoma, secondary CNS involvement, primary skin DLBCL (leg type), primary mediastinal (thymic) large B-cell lymphoma, intravascular large B-cell lymphoma, and primary exudation Lymphoma, T-cell/histiocytosis-rich large B-cell lymphoma, ALK-positive large B-cell lymphoma, plasmablastic lymphoma, lymphoma-like granuloma, EBV-positive mucosal skin ulcer, HHV8+DLBCL, NOS, primary testicular lymphomas. High-grade B-cell lymphoma with MYC, BCL2 and/or BCL6 rearrangement diagnosed by fluorescence in situ hybridization (FISH). B-cell lymphoma has characteristics between DLBCL and classic HL, and cannot be divided into types. Transformed lymphoma. those who have transformed from other types of lymphomas, such as follicular lymphoma, marginal zone B-cell lymphoma, and chronic lymphocytic leukemia/small B-cell lymphoma. History of other malignancy, except for skin basal cell carcinoma and cervical carcinoma in situ and has been in remission without treatment for >/= 5 years prior to enrolment. Severe mental illness. Positive for HIV infection. Positive for HCV infection. Patients who have HBV (+) are eligible. History of anti-CD20 monoclonal antibody treatment for other disease (e.g., rheumatoid arthritis). Previous treatment for NHL, including chemotherapy, immunotherapy, radiotherapy, monoclonal antibody therapy or surgical treatment (except lymph node biopsies diagnostic surgery and biopsy). Participation in another clinical trial in the past 3 months. Vaccination with a attenuated live vaccine within 4 weeks. Use of hemopoietic cytokine in the past 2 weeks, e.g. granulocyte colony stimulating factor(G-CSF). Disease or symptom by the investigator's discretion(interstitial pneumonia, Uncontrollable systemic infections,severe cardiovascular disease (New York Heart Association functional class III or IV, myocardial infarction or unstable arrhythmia or unstable angina in the last 6 months, severe cardiac insufficiency, rogressive multifocal leukoencephalopathy), uncontrolled hypertension (SBP≥180mmHg and/or DBP≥100mmHg), active autoimmune diseases) Known hypersensitivity to any of the study drugs or its ingredients. Prior treatment with anthracycline. DLBCL invaded by special parts such as testis, breast, ovary, etc. Pregnant or lactating women. The researcher believes that it is not suitable for enrollment.