Nails blackened by smashing can usually recover in about 3~6 months. When nails are smashed black, it is considered that the blood vessels under the nails are ruptured, resulting in hematoma under the nails, which leads to the formation of blood stasis. The black blood stasis under the nail will be gradually absorbed by the body, usually about 3~6 months will gradually subside and begin to return to normal. If there is more blood under the nail, you can apply cold compress to stop the bleeding, and then apply hot compress after 24 hours, which can promote local blood circulation and recovery will be faster. If the nail is smashed black, and the black ecchymosis area is relatively large, it is recommended to go to the orthopedics or dermatology department of the regular hospital as soon as possible for consultation and treatment. If the nail is smashed more seriously, which may lead to direct separation of the nail from the nail bed, this situation should be combined with the doctor’s diagnosis and treatment advice as soon as possible, and promptly give the nail extraction treatment, so as to avoid triggering infection, leading to the deterioration of the condition, the consequences will be more serious.