A child was stabbed by an iron nail when walking, the nail pierced the sole of the shoe and entered the foot, and was urgently consulted at a local hospital, where he was given debridement treatment, intramuscular tetanus antitoxin and oral anti-inflammatory drugs, and went home to rest, and the wound gradually healed. The wound healed gradually. However, she had plantar pain from time to time, which was tolerable. More than one month after the injury, the child’s walking pain gradually increased, and he needed to walk with the assistance of crutches. She was examined at the emergency department of our hospital, and was found to have a sinus tract in the middle of the foot, with obvious redness and swelling around the foot, painful to touch, and no obvious fluctuation sensation. ultrasound found tissue edema, with no obvious abscess formation, and foot CT showed that the affected foot was swollen, and there were luminal spaces and sinus tracts present. According to the history of trauma, clinical manifestations and auxiliary examination, the child was diagnosed as having a foreign body residue and infection in the foot, and was admitted to the hospital for anti-infective and surgical treatment. Intraoperatively, a foreign body was found about 50px deep from the plantar aspect of the foot through the sinus tract, which appeared to be a spongy remnant of the sole of a sports shoe. After showing the residue to the family and asking about the situation, it was confirmed that the patient was wearing sports shoes at that time. Therefore, for the plantar iron nail or sharp things after stabbing, need to pay attention to the following points: 1, immediately check the iron nail and other sharp objects have no rust, broken, and no pollution around, and at the same time, carefully check the soles of shoes with or without missing, will be the above information in time to feedback to the treated doctor. 2.After being injured, consult the nearest doctor immediately to clean the wound, pay attention to whether there is any foreign body residue when cleaning the wound; inject tetanus antitoxin or tetanus human immunoglobulin in time, and take antibiotics orally to prevent infection. 3.If the wound is not healed after the injury with pus, redness and swelling for a long time, or if the wound improves at that time and then becomes red, swollen and painful after a period of time, it is necessary to highly suspect that there is no foreign body residue.