This is a prospective, double-blinded, single center, randomized clinical trial. It compares the clinical efficacy and safety of thees 2 drugs in the treatment of active Takayasu's arteritis patients.

In this study, 40 Takayasu's arteritis patients with active disease will be enrolled. Patients are randomized into the tofacitinib treatment group and prednisolone treatment group. Patients will follow the same reduction steps for prednisolone and its placebo. The primary end point is the percentage of patients who are in complete response at week 24.

The efficacy will be evaluated at week 4, 12 and 24. Safety is also monitored during the study.

Inclusion Criteria:

1. Patients aged between 18-65 years old;
2. Fulfilled the classification criteria of Takayasu's arteritis by ACR 1990;
3. Active TAK: defined by the definition of active disease in the recommendations released by EULAR in 2018 or Kerr's criteria by NIH;
4. Patients who signed the informed consent form.

Exclusion Criteria:

1. Patients who failed or intolerant to either tofacitinib or its similar drugs;
2. Patients with severe liver disease defined by the serum ALT or AST elevated more than 2 times the upper limits;
3. Not well controlled diabetes;
4. Moderate and severe hyperlipedimia;
5. Patients with history of thrombus;
6. Uncontrolled heart failure od renal dysfunction (eGFR <30ml/min);
7. Patients with active infection, including tuberculosis, hepatitis B and C, HIV infection, bacterial or fungal infection;
8. Upper GI bleeding happened in 3 months before enrollment;
9. Refractory hypertension;
10. Pregnant or intended to be pregnant recently;
11. Severe coronary artery involvement demonstrated by CTA;
12. Severe cranial or cervical or renal artery diseases that need surgery;
13. Patients that should not be included judged by the investigator.