There are many reasons that lead to the left pelvic pain, the common ones are bone tumor, hip joint disease, femoral head necrosis, pelvic inflammatory disease, etc., as follows: First, bone tumor: the presence of bone tumor on the patient’s pelvic bone, such as primary bone tumor or metastatic bone tumor, which can lead to the presence of left pelvic bone with obvious pain symptoms, in order to make a definitive diagnosis, you need to carry out a local common X-ray, CT, and magnetic resonance imaging examination; Hip joint disease, femoral head necrosis: if the patient has left hip synovitis, osteoarthritis of the hip joint, hip dysplasia, and necrosis of the femoral head, it will lead to obvious pain symptoms in the left pelvis, and localized MRI examination is needed to make a clear diagnosis; 3. Pelvic inflammatory disease: if the patient has pelvic inflammatory disease, the stimulation of pelvic nerves will lead to obvious pain symptoms in the left pelvic bone. Pelvic inflammatory disease: if the patient has pelvic inflammatory disease, it will stimulate the nerves on the pelvis, which will also lead to obvious pain symptoms in the left pelvis.