Efficacy and Safety of Yuxuebi Tablet in Treating Night Pain of Ankylosing Spondylitis (AS).

Inclusion Criteria: 1. Ages 18-65, male or female 2. Confirmed diagnosis of Ankylosing Spondylitis 3. Syndrome of traditional Chinese medicine is blood stasis syndrome 4. ASDAS-CRP (Ankylosing Spondylitis Disease Activity Score)≥2.1 5. Visual analogue scale (VAS) for night pain≥4分 6. Maintained stable doses of Sulfasalazine, Methotrexate, Leflunomide, etc. for more than 1 month if treating with Slow-Acting Antirheumatic Drugs 7. Maintained stable doses of biologics for more than 3 month if treating with biologics 8. Not use Nonsteroidal Antiinflammatory Drugs within 2 weeks 9. Patients who have not participated in other clinical trials within 4 weeks 10. Written informed consent Exclusion Criteria: 1. Pregnant or breastfeeding or who expecting to conceive 2. Psoriatic arthritis or Enteropathic arthritis 3. AS with iritis or uveitis 4. Abnormal liver function 5. Abnormal kidney function，high level of Creatinine 6. WBC (White Blood Cell)\<3.0×10\^9/L or with Hematological Disease 7. Patients with poor control of hypertension or diabetes 8. Acute or chronic infectious diseases 9. Severe arrhythmia 10. Patients with malignant tumors or with a history of malignant tumors 11. Drug allergy 12. Patients who had taken Yuxuebi tablet for more than 4 weeks with poor outcome 13. Patients who are treating with Traditional Chinese medicine for promoting blood circulation and removing blood stasis 14. Alcohol or drug abuse 15. Participants who are not suitable for clinical trial under doctors' consideration.