There are three possibilities for the finger to be swollen after being injured by a nail, firstly, local soft tissue edema, secondly, local hematoma formation, and again, local bacterial infection, which needs to be judged according to the patient’s symptoms, signs, and relevant examinations. 1. Edema: after the finger is nailed, can cause damage to the local soft tissue, soft tissue can appear oozing edema. 2. Hematoma: Nail injuries can lead to bleeding when blood vessels are injured, and because of the small external opening of nail injuries, blood is not easily discharged and accumulates in the soft tissues of the finger, which can easily form a hematoma. 3. Infection: After a nail puncture wound, if the wound is not thoroughly cleaned and disinfected, the wound is susceptible to bacterial invasion and infection. Especially tetanus and other anaerobic bacteria, the finger can appear typical symptoms of redness, swelling, heat and pain. After the finger is nailed, it is recommended to seek medical treatment in time, given by professional doctors to clean and disinfect the wound, inject tetanus antitoxin or tetanus immune globulin, if necessary, the use of amoxicillin and other antimicrobial drugs to prevent infection, the drug needs to be used under the guidance of a professional physician.