Study of Iguratimod Plus Methotrexate Compared to Leflunomid Plus Methotrexate in Patients With Rheumatoid Arthritis

Inclusion Criteria: * Subjects with a diagnosis of RA according to the diagnostic criteria of the American College of Rheumatology (ACR) (revised in 1987) * Rheumatoid Arthritis for more than 3 months from the time of the initial diagnosis * Functional Class II-III * Subjects have active RA at the time of screening * Subjects with inadequate response to biologics should have a washout period before the initiation of study. For etanercept, washout period should be 2-week, and 8-week for infliximab and adalimumab. * For firstly diagnostic RA patients, the disease activity should be moderate to severe, with DAS28\>3.2 * Must have at least 4 tender joints (66 join count) and 8 swollen joints( 68 join count) at screening and baseline * Has a C-reactive protein ≥ 10 mg/L(or 1.0 mg/dL) OR Erythrocyte Sedimentation Rate (ESR) ≥ 28 mm/hr * Must have a negative Pregnancy test and use adequate method of contraception throughout the trial * Written informed consent Exclusion Criteria: * Preceding treatment with DMARDs, immunosuppressants (cyclophosphamide, cyclosporine, azathioprine, etc.), or Tripterygium within 4 weeks prior to study entry * Subjects have been treated with iguratimod or leflunomide combined with MTX before screening. * Subjects combined with other autoimmune disease, such as systemic lupus erythematosus (SLE), mixed connective tissue disease (MCTD), scleriasis and polymyositis, except for Sjögren syndrome. * Chest x-ray abnormalities, such as tuberculosis, interstitial pulmonary fibrosis, etc. * ALT \>1.5×ULN, AST \>1.5×ULN, Cr \>135umol/L, total bilirubin\>1.5×ULN * WBC\<4×109/L，HGB\<85g/L，PLT\<100×109/L * Subjects with serious cardiovascular, renal, hematologic, endocrine diseases or malignant * Women of Pregnant or breastfeeding, and male or female with recent plan to conception * Subjects with immunodeficiency, uncontrolled infection and active gastrointestinal disease * Allergic to any of the study drugs * History of alcoholism * Subjects with mental illness * Subjects receiving live vaccines recently * Subjects participating in other clinical study within 3 months prior to study entry