This paper introduced the experience in the treatment of ankylosing spondylitis from the syndrome of yin deficiency and dampness-heat. The important influence of yin deficiency on the pathogenesis was discussed from the etiology, pathogenesis, clinical prognosis and other aspects. The formation causes of dampness-heat and its significance in the development of the disease were analyzed. Kidney deficiency and dampness-heat stasis were considered as the important pathogenesis of ankylosing spondylitis. Yin deficiency in kidney was the basis of the disease,while the dampness-heat was not only the pathogenic factors but also the main pathological product that throughout the disease. The therapy of nourishing yin and tonifying kidney and clearing and reducing dampness-heat shows good clinical effect in the treatment of ankylosing spondylitis.