The hidden pain on the left inner side of the left side of the pelvis in men may be physiological, and there may be pathological factors such as synovitis of the hip joint, osteoporosis, glenoid labral injury, necrosis of the left femoral head and other diseases. 1. Physiological factors: If there is long-term chronic weight-bearing activities such as sedentary activities and standing on the left side of the pelvis, it may cause an increase in muscle tension on the left side of the pelvic bone, leading to the accumulation of lactic acid and pain, and the symptoms can be gradually alleviated by resting more. 2.Pathologic factors (1) Hip synovitis: it is mainly related to frequent weight-bearing walking such as hiking, going up and down the stairs, etc., which irritates the synovial membrane and leads to the increase of synovial secretion of synovial fluid, and if the lesion occurs on the left side, it may be manifested as the accumulation of fluid in the hip joint on the left side of the pelvis, pain, swelling and other symptoms. (2) Osteoporosis, such as the left side of the pelvis in the elderly with severe osteoporosis, the lesion can produce pain. (3) Labral injury: mainly related to hip dysplasia or traumatic impact, etc. When the injury occurs on the left side, it may cause pain on the left side of the pelvis, and may be accompanied by joint soreness and swelling. (4) Left-sided necrosis of the femoral head: due to heavy drinking, smoking and other factors that damage the blood supply of the femoral head, causing ischemic necrosis of the femoral head on the left side of the early stage of the disease can be manifested in the left medial pelvic pain that is the deep pain in the hip joint. (5) Other diseases: such as ulcerative colitis, urinary stones, etc. can also produce local stimulation caused by the left inner pelvic pain. Excluding physiological factors, the male left side of the pelvic bone medial pain should be timely consultation, improve the pelvic ultrasound and other examinations, to identify the cause of active treatment, so as not to delay the condition.