In clinical practice, we often encounter patients with ankylosing spondylitis who have limited limb and joint function due to various reasons of underdiagnosis and misdiagnosis. While we are saddened by the regret, we feel that it is significant for the early diagnosis and treatment of various rheumatic diseases. For ankylosing spondylitis. For those aged between 10-40 years old, especially men, attention needs to be drawn to the following conditions if they occur and sacroiliac joint films, HLA-B27 and other tests are performed for early diagnosis and treatment. 1.Persistent pain in the lower back or low back, aggravated after holding a position for a longer period of time and reduced after activity. 2.Single pain or/swelling in the knee, ankle or heel of the lower limbs. 3.Persistent pain in the hip or Achilles tendon. 4.Uveitis of the eye. 5. Progressive worsening of stiffness and pain and limitation of movement in the low back. In addition, a family history of ankylosing spondylitis with the above mentioned symptoms should be highly suspected of this disease.