Study Purpose and Design: A Multi-center, Randomized, Double-blind, Placebo-controlled Study to Evaluate the Safety, Tolerability and Pharmacokinetics of Single Ascending Dose and Multiple Ascending Doses of TJ003234 in Rheumatoid Arthritis Patients.

Inclusion Criteria:

• Subjects must be ≥ 18 and ≤70 years old when signing the informed consent, with no limitation of gender.
• Established Rheumatoid arthritis patients, diagnosed by ACR/EULAR criteria 2010 at least 6 months prior to randomisation.
• Single Ascending Dose: DAS28 score≤3.2. Multiple Ascending Dose: DAS28 score≤5.1 and >3.2.
• Allowed one or more standard treatments, but the start date should no later than 12 weeks(84 days) before the randomisation and should take at a stable dose more than 4 weeks(28 days) before the randomisation. The combination taken of Methotrexate (MTX) and leflunomide was not allowed within 4 weeks (28 days) before randomization.
• Subjects must agree to attendance the study and signed the inform concent by themselves.
• Subjects(include subjects's wife) are no pregnancy plan during the sceering and 3 months after complete the study and agree to use contraceptives that protocol suggest.

Exclusion Criteria:

• Employees of the hospital or any other person that paticipant in the study and their immedidte family members.
• A documented history of an autoimmune disease other than RA (other than secondary Sjögren's syndrome) .
• Previous received Any biologic DMARD therapy including tsDMARD. •A positive hepatitis B (HBsAg, anti-HBc, and/or IgM anti-HBc), hepatitis C or HIV test at screening, indicative of a current or past infection.
• A history of active tuberculosis (TB) or positive serological test for TB (Quantiferon TB Gold or T-SPOT).
• Female patients who are pregnant during the study, or are breastfeeding. •Malignancy, or prior malignancy, with a disease free interval of <5 years after diagnosis and intervention except curative treatment for basal and squamous cell skin cancer.

Double-blind