Study of SHR0302 Tablets (SHR0302) as Monotherapy in Active Rheumatoid Arthritis (RA) Patients

Inclusion Criteria: * male or female subjects who are 18 - 70 (inclusive) years of age on the day of signing informed consent * have a diagnosis of RA meeting the 2010 ACR/EULAR criteria of RA and ACR functional class I-III * have ≥6 swollen joints (from a 66-joint count) and ≥8 tender joints (from a 68-joint count) at Screening and at Baseline, Screening serum c-reactive protein (CRP)or hsCRP \> 1.2 x upper limit of laboratory normal range (ULN),or erythrocyte sedimentation rate (ESR) \> 28 mm/h * have not used any disease modifying anti-rheumatic drug (DMARD) or have an inadequate response to one or more kinds of conditional DMARDs (methotrexate, leflunomide, Chloroquine, hydroxychloroquine, sulfasalazine, minocycline, penicillamine, auranofin or injection gold preparation, and iguratimod) due to lack of efficacy or toxicity, and have agreed to be washed out from these conditional DMARDs for a period of at least 7 t1/2s prior to randomization, with the exception of antimalarials, which must be at a stable dose for at least 12 weeks prior to randomization * Body mass index (BMI = weight/height squared (kg/m2)) within the range of 18 to 35, Exclusion Criteria: * current or previous RA treatment with a jak inhibitor * current or previous RA treatment with a biologic DMARD