Ice is a part of the post-operative rehabilitation process of ACL reconstruction that cannot be ignored. When patients perform leg bending exercises, they will inevitably experience joint swelling, pain, and even bleeding, and icing at this time can effectively eliminate swelling, relieve pain, and reduce bleeding. Generally speaking, ice is applied after the stitches are removed and the bandages are removed after surgery. Ice must be applied around the knee joint for 20 minutes after each leg bend, and 3-4 times on average at other times, i.e. 4-6 times per day, with an interval of 60 minutes or more between ice applications. It is important to note that ice is not placed directly on the knee joint, but rather ice and water are mixed in a 1:1 ratio, and the ice is applied in the form of an ice water mixture, the amount of which can be adjusted according to the size of the knee joint. In addition, a towel can be wrapped around the ice water mixture to prevent frostbite. For patients shortly after surgery, a layer of plastic wrap can be placed between the wound gauze and the ice pack to prevent water from flowing into the wound and affecting recovery. By 2-3 months after surgery, the patient will be able to move the knee very freely, and if there is no more pain or swelling during rehabilitation or daily activities, the number of ice packs can be reduced or even stopped.