Summary of case history,　Patient Zhang, male, 37 years old, presented with "intermittent lumbosacral pain for more than 12 years and left heel pain for 2 months" on July 1, 2021. The patient developed lumbosacral pain with no apparent cause 12 years ago, and was diagnosed with "ankylosing spondylitis" in an external hospital. The patient was treated with "Tripterygium Glycosides, Celebrex, and thymosin enteric-coated tablets" intermittently, while the symptoms were under fair control In the past 2 months, the patient suffered from pain in the left heel due to exertion, and the pain was not well controlled after taking "Tripterygium Glycosides" by himself. Current symptoms: the patient had pain in the lumbosacral region and in the heel of the left foot, which was obvious in the morning, without dry mouth or bitterness, coldness around the body, not much sweating, unshaed stools 2-3 times a day with abdominal pain before stool.,TCM diagnosis,　Dyphosis(kidney deficiency and du deficiency, spleen deficiency and dampness excess syndrome),Western medicine diagnosis,　Ankylosing spondylitis.,Therapeutic methods,　This disease should be treated by warming kidney and strengthening governor, invigorating spleen and dispelling dampness, and relieving pain through the ligaments. Wenshen Jianpi Dingji Decoction was chosen as the basic formula for treatment.,Clinical outcomes,　After the treatment with Wenshen Jianpi Dingji Decoction for more than 6 months, the clinical symptoms were not only effectively improved, but also the structural damage of the sacroiliac joint was reversed, and clinical remission was achieved.