The most common cause of swelling and pain in the left buttock is due to acute injury and chronic strain injury, resulting in chronic inflammation of the buttock muscles and their soft tissues leading to the appearance of pain symptoms, which can occur due to overloaded activities of the lower limbs in daily work or acute injury caused by sports. Due to lumbar spine disease, there is compression of the sciatic nerve root in the lower limb, resulting in abnormal sensation in the sciatic nerve course area, which can also cause buttock swelling and pain. It can also be seen in the soft tissue infection around the buttocks, can be seen in the perianal infection or buttock soft tissue infection, will also produce the corresponding symptoms of swelling and pain.