Inclusion Criteria:

          1. Diagnosed as diffuse large B-cell Lymphoma with positive CD20 results;

          2. Age between 18 to 70 years old;

          3. World health organization-Eastern Cooperative Oncology Group Performance Status (ECOG)
             0-2;

          4. No history of malignant tumors, having no tumor other than DLBCL at the time of
             enrollment;

          5. Life expectancy no less than 6 months;

          6. The patient or his/her attorney would be able to provide written consent for necessary
             examinations or procedures;

          7. Ann Arbor stage I~ IV

          8. previously untreated advanced DLBCL.

          9. At least one bi-dimensionally measurable lesion (greater than [>] 1.5 centimeters in
             its largest dimension by CT scan or magnetic resonance imaging)

         10. Availability of a representative tumor specimen and the corresponding pathology report
             for retrospective central confirmation of the diagnosis of DLBCL.

         11. Agree to remain abstinent or use contraceptive measures.

        Exclusion Criteria:

          1. History of autologous stem cell transplantation,radiotherapy or chemotherapy.

          2. History of other malignant tumors, except skin basal cell carcinoma and in situ
             cervical cancer;

          3. With uncontrolled cardiovascular/ cerebrovascular disease, coagulation disorders,
             connective tissue disease, severe infectious diseases;

          4. Lymphoma originated in the central nervous system;

          5. Left ventricular ejection fraction ≦50％;

          6. Abnormal lab results in enrollment:Neutrophil count: <1.5*10^9/L；Platelet count
             <75*10^9/L；AST or ALT >2 times the upper limit of normal level，AKP and total bilirubin
             >1.5 times the upper limit of normal level;serum creatinine >1.5 times the upper limit
             of normal level;

          7. Other uncontrolled medical conditions which the investigators think might influence
             the results of the trial;

          8. Patients with mental illnesses or other diseases that might not comply with the trial
             plan;

          9. Women during pregnancy or lactation;

         10. HIV positive patients;

         11. HbsAg (+) patients with HBV DNA(+), can be enrolled only when his/her HBV DNA turns
             negative; patients with HBsAg(-) HBcAb(+) can be enrolled only when his/her HBV DNA
             turns negative;