The yellow water flowing from knee abrasion needs to be treated accordingly to the wound condition. 1. The degree of wound breakage is small: the skin damage is shallow, you need to carry out a thorough debridement, remove all the surface dirt and foreign matter, clean the wound can be exposed after cleaning, avoid contact with moisture, reduce movement. Then bandage the wound with band-aid or sterile gauze, and change the treatment regularly. 2. Large degree of wound breakage: after knee injury, due to a large number of skin defects, subcutaneous fat layer exposure, need to carry out a comprehensive debridement, remove contamination, necrotic tissues and foreign bodies, through the suture to reduce the trauma, and then bandaged with sterile gauze, regular dressing changes, removal of stitches. And be taken amoxicillin, cefaclor and other antibiotics to prevent infection. Knee abrasion need to pay attention to check whether there is patella or knee joint injury, if so, also need to visit the orthopedic department. There is obvious skin damage, should be injected with tetanus antitoxin to prevent tetanus.