The waist is concave in the front and the stomach is convex in the front, often due to the following etiologies. 1, there may be excessive lumbosacral angle, which is often more common in women. Due to congenital hereditary factors, it will lead to the part where the lumbar and sacral vertebrae intersect, the angle becomes larger, and the S-shaped curve looks more obvious in the back. This situation will lead to the patient’s abdomen convexity forward, and it is easy to have pain in the lumbosacral area. 2. It may be caused by the slippage of the vertebrae of the lumbar spine. For example, due to genetic factors or acquired trauma, the patient has a fracture of the lumbar isthmus, at which time the vertebrae of the lumbar spine will slip forward. In the process of the patient standing upright, there may be excessive bending of the lumbar spine, which in turn leads to the above-mentioned situation. 3, may be caused by the anterior tilt of the pelvis. In such patients, it is often due to too weak muscle strength in the front. The strength in front of the abdomen and hip joint is weak, which will lead to an imbalance in the muscle strength around the pelvis, which in turn produces an anterior pelvic tilt, resulting in the above symptoms. 4, may be caused by congenital hip dislocation. Once such a disease is produced, it will also show the above deformity.