Abstract： From the perspective of combined internal and external pathogens in traditional Chinese medicine theory， combined with genetic factors， infection factors and immune factors in modern medicine，it is concluded that endogenous pathogens are the fundamental factors and necessary conditions for the onset of ankylosing spondylitis，and external pathogens are important inducements. The treatment should focus on reinforcing healthy qi and dispelling pathogen with both attack and supplementation，clear internal pathogens， and defend external pathogens， so as to control the development of the disease， improve clinical symptoms，and reduce its recurrence.