The causes of pain inside the big crotch are: 1, the most serious may be metastatic foci of cancer, should be excluded whether the combination of other neoplastic diseases, if the combination should be given great importance.2, the big crotch pain inside the consideration is sacroiliac joint inflammation, with osteophytes or congenital dysplasia or trauma deformities related to the healing of the 3, the big crotch pain inside the consideration of necrosis of the femoral head or the inflammation of the hip joint caused by the 4, the big crotch pain inside the consideration of lumbar disc hernia compression of the nerves governing the crotch muscles. The pain is considered to be caused by the lumbar disc herniation compressing the nerves innervating the hip muscles.5, the pain inside the big hip is considered to be caused by rheumatoid arthritis, rheumatoid arthritis is easy to involve the big joints, most of them are symmetric, wandering pain.6, the elderly fall, car accident and other violent injuries caused by the big hip inside the pain, we should be highly suspicious of the existence of the fracture of the neck of the femur, femur fracture, or there is the case of dislocation of the hip joint. It is recommended to go to the regular hospital to improve the pelvic orthosis. It is recommended to go to the regular hospital to improve the pelvic X-ray, hip magnetic resonance, lumbar spine CT examination, to clarify the cause of the next step in the treatment.