Straightening of the lumbar curvature, i.e., the disappearance of the normal physiological convexity of the lumbar spine, may be due to long-term poor posture and other physiological reasons, but also due to lumbar disc herniation, ankylosing spondylitis, surgical trauma and other pathological reasons. 1. Physiological reasons: the normal human lumbar spine will have a physiological curvature that protrudes toward the front, known as the normal curvature. When the human body’s prolonged postural errors are not corrected, it may lead to the disappearance of physiological curvature, lumbar vertebrae straighten or even backward convexity, such as long-term sedentary standing people, hunchbacked heavy laborers and so on. 2. Pathological causes: including lumbar degenerative disease caused by lumbar disc herniation, ankylosing spondylitis, rheumatoid arthritis and other autoimmune diseases, lumbar spine fusion surgery after the treatment of patients. Pathologic causes can lead to osteophytes, loss of muscle strength in the lumbar region, narrowing of the vertebral space, and even direct vertebral fusion, resulting in the loss of lumbar curvature and straightening of the lumbar curvature. There may also be other reasons for the straightening of lumbar curvature, so it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment or therapy under the guidance of the doctor.