Cold compress for scalp hematoma is usually applied within 24h after injury, the purpose of cold compress is to make the local scalp temperature drop significantly, after the temperature drop, the small scalp arteries will be stimulated by low temperature, will appear spasm and contraction, so that the lumen of the artery becomes smaller or completely occluded, thus reducing the bleeding of the artery, so that the volume of the scalp hematoma is reduced, which is conducive to the absorption of the scalp hematoma in the future. However, after 24 h, the blood clot in the scalp blood vessels has completely coagulated, so instead of constricting the blood vessels and stopping the bleeding, a local hot compress can be applied. The purpose of the hot compress is to stretch the veins and lymphatic vessels of the scalp, thus facilitating the absorption of the hematoma.