Bruising after leg pain is commonly caused by trauma, and may also be caused by diseases such as leukemia or hemophilia. 1. caused by trauma: trauma is easy to capillary rupture resulting in bruising, if there is a history of trauma, within 72 hours using intermittent cold compresses, 72 hours after the use of hot compresses, but also can be taken orally to activate blood circulation and remove blood stasis of drugs such as Panax ginseng tablets. 2. Leukemia: If there is leukemia, the leukemia tumor cells will reach the bone tissues through the systemic circulation, which will cause bone destruction and the symptoms of leg pain, and leukemia will also lead to platelet abnormality and the symptoms of bruising. 3. Hemophilia: As the condition of hemophilia worsens, it will stimulate inflammation in the joints of the legs of the patients, so that the patients’ legs will be red, swollen and painful, and hemophilia will lead to coagulation dysfunction, so there will be bruises. Bruising after leg pain may also have other causes, it is recommended to go to the hospital in a timely manner to find out the specific cause of the disease, under the guidance of the doctor to treat the cause.