A Study of LNK01001 Capsule in Moderately to Severely Active Rheumatoid Arthritis

Inclusion Criteria: * Participants between ≥ 18 and ≤70 years of age. * Diagnosis of RA for ≥ 3 months at screening visit who also fulfill the 2010 American College of Rheumatology (ACR)/ European League Against Rheumatism (EULAR) classification criteria for RA. * ≥ 6 swollen joints (based on 66 joint counts) and ≥ 6 tender joints (based on 68 joint counts) at Screening and baseline visit. * High-sensitivity C-Reactive Protein (hsCRP) ≥ ULN at Screening. * Participants have been receiving csDMARD therapy ≥ 3 months and on a stable dose for ≥ 4 weeks prior to the first dose of study drug. Exclusion Criteria: * Subjects who are allergy to any component of the study drug. * Subjects who are ACR functional class IV or long-term bedridden/long-term wheelchair. * Prior exposure to Janus Kinase (JAK) inhibitor (including but not limited to tofacitinib, baricitinib, and filgotinib). * Subjects who received intra-articular, intramuscular, intravenous, trigger point or tender point, intracapsular, or intra-tendon injections of glucocorticoids within 8 weeks before randomization. * Current use of oral or inhaled glucocorticoids and the daily dose is \>10 mg of prednisone (or equivalent dose) or on a not stable dose within 4 weeks before randomization. * Current use of Non-steroidal anti-inflammatory drugs and on a not stable dose within 4 weeks before randomization. * Subjects who received iguratimod treatment within 4 weeks before randomization. * Subjects who received interferon treatment within 4 weeks before randomization. * Current diagnosis of systemic inflammatory disease other than RA. * History of malignancy or current diagnosis of malignancy within 5 years before screening visit. * Uncontrolled diabetes, hypertension, kidney disease, liver disease, severe heart disease. * Subject with any major surgery within 4 weeks before randomization or planned major surgery during study; history of chronic pain that may affect study evaluation; previous recipient of an organ transplant. * Any clinically significant laboratory or ECG abnormal value, as determined by the Investigator, may interfere with the evaluation of the study results.