The patient’s knee suddenly purple, generally common clinical causes are mainly the following situations: a. accidentally fall during strenuous activities at the knee soft tissue, can cause local capillary rupture, appear local bruising, at this time need to give local ice as soon as possible, to avoid capillary rupture aggravated, causing bruising increasing range. At the same time, it can be combined with external application of blood-stasis activating cream, infrared irradiation physiotherapy, oral administration of medicine such as mai zhi ling, swelling and pain to improve the blood circulation of the injured place, promote the faster recovery of the local injured soft tissue and reduce the symptoms of bruising. Second, varicose vein patients often have obvious varicose veins at the knee, if the local blood vessels suddenly rupture, it will be accompanied by bruising symptoms. At this time, it is recommended to use elastic bandage to stop bleeding with local pressure. If conservative treatment is not effective, surgery is needed to ligate the varicose blood vessels if necessary to completely remove the symptoms of bruising at the knee.