The ilium is one of the components of the hip bone, and left iliac pain may be caused by chronic strain injury, soft tissue trauma, sacroiliac joint tuberculosis and other reasons. 1. Chronic strain injury: due to local compression, friction or poor posture during long-term exercise, resulting in chronic strain inflammation of the surface attached muscles and ligaments, the left iliopsoas pain can occur. 2. Soft tissue trauma: when the left ilium is hit by violence, or external impact, etc., which can cause muscle and ligament injuries around the left ilium, and left iliac pain can occur, and can be accompanied by localized swelling, subcutaneous bruising and other symptoms. 3. Sacroiliac joint tuberculosis: the infectious lesion caused by Mycobacterium tuberculosis invading the cartilage or bone tissue of sacroiliac joint and destroying the sacroiliac joint surface and bone tissue. Patients may have left iliac pain, which is alleviated at rest and aggravated after activities, and may be accompanied by abscesses, dysfunction and other symptoms. Left iliac pain can also be seen in other diseases, it is recommended that patients go to the hospital in a timely manner, follow the doctor’s instructions for treatment, to avoid delaying the condition.