Prospective, Randomized, Multicenter, Control Study to Assess the Efficacy and Safety of Tacrolimus in Induction and Maintenance Phase Treatment in Lupus Nephritis

Inclusion Criteria: 1. Subjects of either sex, 14-65 years of age; 2. Diagnosis of SLE according to the ACR criteria(1997); 3. Kidney biopsy within the 6 months prior to first randomization with a histologic diagnosis (ISN/RPS 2003 classification of LN) class III, IV, V; 4. Class IV LN: proteinuria \>1g/24hr or Scr\>115umol/L; 5. Class III or V LN: proteinuria \>2g/24hr or Scr\>115umol/L; 6. Provision of written informed consent by subject or guardian. Exclusion Criteria: 1. Inability or unwillingness to provide written informed consent ; 2. Known hypersensitivity or contraindication to tacrolimus, cyclophosphamide , azathioprine, corticosteroids; 3. Usage of immunosuppression therapy (MMF, CTX, CysA, MTX ect) for more than 1 week within 1 month prior to first randomization; 4. Pregnancy, nursing or use of a non-reliable method of contraception; 5. Continuous dialysis starting more than 2 weeks before randomization into the induction phase and/or continuous dialysis with an anticipated duration of more than 8 weeks; 6. Previous kidney transplant or planted transplant; 7. Scr \> 4mg/dl (353umol/L); 8. Active hepatitis, with liver dysfunction; 9. Diagnosed DM; 10. Participation in another clinic trial and/or receipt of investigational drugs within 4 weeks prior to screening .