This is a prospective randomized controlled study to evaluated the efficacy and safety of kunxian capsule in treating of patients with early ankylosing spondylitis (AS). The major outcome index is proportion of patients achieving ASAS20 response at week12, and minor outcome indexes include ASAS50 and ASAS70, BASDAI20,BASDAI50 and BASDAI70. The adverse events at any time were recorded to evaluate the safety.

Inclusion Criteria:

• 16 to 65 years old, having signed the informed consent;
• fulfill the ESSG criteria for diagnosis of SpA; not fulfill the 1984 modified NewYork criteria for AS;
• BASDAI score more than 4;
• stop taking DMARDs for at least 4 weeks;
• NSAIDs dosage has been stable for at least 4 weeks;

Exclusion Criteria:

• Intra-articular injection of cortisone within 3 months.
• History of heart failure, multiple sclerosis, COPD, lymphoma or other tumors;
• Accompanied by fibromyalgia or other rheumatic diseases;
• Female of pregnancy or breast feeding;
• History of mental disease and poor compliance.
• History of drug abuse or alcoholism.