A Study to Compare the Efficacy and Safety of Tacrolimus Capsules and Cyclophosphamide Injection in Treatment of Lupus Nephritis

Inclusion Criteria: * 18.5≤Body Mass Index (BMI) \<27; * Diagnosed as systemic lupus erythematosus (based on American Rheumatism Association Diagnostic Criteria 1997) * Diagnosed as III, IV, V, III + V, IV + V lupus nephritis (according to the LN classification in International Society of Nephrology and Renal Pathology Society (ISN/RPS) 2003) within 24 weeks before enrollment with renal biopsy; * 24-hour urine protein ≥ 1.5g, Scr\<260umol/L (or 3mg/dL) Exclusion Criteria: * Class II or VI lupus nephritis or renal biopsy chronic index (CI) \> 3 or with TMA; * Received immunosuppressants (mycophenolate mofetil (MMF), cyclosporine, methotrexate, mechlorethamine, chlorambucil, tripterygium preparations, leflunomide etc.) treatment with a duration of more than one week within 30 days prior to enrollment; * Received tacrolimus (except for topical use) or cyclophosphamide treatment within 30 days prior to enrollment; * Received a course of methylprednisolone (MP) pulse therapy or gamma globulin treatment or plasma exchange within 30 days prior to enrollment; * Patients with history of allergies to tacrolimus, cyclophosphamide or methylprednisolone; * Pregnancy, lactation or patient unwilling to take contraceptive measures; * Patients with estimated maintenance dialysis for more than eight weeks; or dialysis for more than two weeks prior to entering observation; * Patients received kidney transplantation or plan to have kidney transplantation recently; * Serum creatinine (Scr) ≥260umol/L (or 3mg/dL) or creatinine clearance rate (Ccr) \< 30ml/(min.1.73m2); according to Cockcroft-Gault formula: Ccr (ml/sec) = \[(140- age)× Weight (kg)\] × K / \[72×Scr (umol/L) ×0.6786\], Female K = 0.85, Male K = 1.0; * Patients suffering from liver dysfunction (aspartate aminotransferase (AST) or alanine aminotransferase (ALT) more than 3 times the upper limit of normal lab value) or bilirubin more than 3 times the upper limit of normal lab value; * Patients diagnosed with diabetes; * History of gastrointestinal bleeding or pancreatitis within 3 months; * Uncontrollable hyperkalemia after dietary therapy or reduction of potassium treatment (exceed the upper limit of normal lab value); * Patients suffering from lupus pneumonia or lung injury; * Patients with anemia (hemoglobin \<7g/dl) or bone marrow suppression (WBC \<3.0×109/L, and/or neutrophils \<1.5×109/L, and/or platelets \<50×109/L) not secondary to systemic lupus erythematosus; * With congenital heart disease, arrhythmia, heart failure or other severe cardiovascular diseases; * With refractory hypertension (defined as blood pressure still exceeds 180/110 mmHg despite taking three different types of antihypertensive drugs \[one of them is diuretic\] simultaneously); * Patients with recurrent tumors within 5 years; * Severe infection that requires intravenous antibiotics within 2 weeks prior to enrollment; * Patients with infection of hepatitis B virus or hepatitis C virus; patients with active tuberculosis; patients with severe immunodeficiency diseases (including active cytomegalovirus infection (positive CMV IgM antibody), or human immunodeficiency virus (HIV) infection, etc.); * Patients with lupus encephalopathy or other life-threatening complication of systemic lupus erythematosus; * Patients participated in other clinical trials within three months before enrollment