Normal blood sedimentation C-reactive protein in ankylosing spondylitis usually suggests that the patient is not currently in the active phase of inflammation, and the condition is relatively stable. Ankylosing spondylitis is an autoimmune disease, mainly characterized by sacroiliac arthritis and attachment point inflammation, manifested as lower back pain with morning stiffness, which is heavier at night or during sedentary time, and is alleviated after activities. It can also be seen in ankle and knee pain, and some patients can have recurrent episodes of uveitis and iritis. C-reactive protein is an indicator of inflammation and is elevated in plasma when the body is infected or injured.C-reactive protein activates complement, which removes disease-causing microorganisms and damaged tissue cells from the body, and plays a regulatory role in the natural immune process. If the C-reactive protein is normal, the organism may not be diseased. In the other case the C-reactive protein, although normal, does not mean that the organism is free of disease, but only that these diseases may not lead to abnormal C-reactive protein or are in the stabilization phase of the disease. In case of ankylosing spondylitis, it is recommended to consult a doctor, check C-reactive protein in time and treat the disease under the doctor’s advice.