There are several possible causes of pain in the middle of the waist and buttocks: first, fasciitis of the gluteal muscles, when there is fasciitis of the gluteal muscles, there can be pain in the upper part of the buttocks, often localized stabbing pain or pins and needles pain, often caused by cold or exertion. The pain can occur when there is chronic inflammation of the dermatomal nerve in the upper part of the hip, often a palm-sized pain, which requires nerve nutrition and local closure treatment; third, sacroiliac arthritis, when there is sacroiliac arthritis, there can also be pain in the lumbosacral region in the middle of the waist and hip, which should be diagnosed by X-ray examination of the lumbosacral spine; fourth, ankylosing spondylitis, patients with ankylosing spondylitis can also have pain in the sacroiliac joint in the middle of the waist and hip. Fifth, dense osteoarthritis, patients with dense osteoarthritis can have pain in the middle of the waist and buttocks, which should be diagnosed and treated by CT examination of the sacroiliac joint.