In recent years, the incidence of clinically encountered reactive arthritis is increasing, especially in young people, which warrants vigilance! The diagnostic criteria are outlined as follows: 1. typical peripheral arthritis asymmetric arthritis of the lower extremities predominantly Wen Chengping, Department of Traditional Chinese Medicine Immunology and Rheumatology, Third Affiliated Hospital of Zhejiang University of Traditional Chinese Medicine 2. evidence of antecedent infection: (1) weeks before the manifestation of urethritis such as diarrhea or urinary urgency and astringency; (2) although the symptoms of infection are not obvious, but there is laboratory evidence of infection, such as examination can be found Salmonella, Chlamydia, gonococcus, type B (2) laboratory evidence of infection, such as Salmonella, Chlamydia, gonococcus, Streptococcus hemolyticus, etc. In addition, other arthritis should be excluded: e.g. psoriatic arthritis, infectious arthritis and gouty arthritis.