Black threads after the incision has healed may be caused by suture rejection, or the removal of the suture is not clean. If non-absorbable sutures are used for incision healing, the sutures need to be removed. After the incision is healed, the body can not absorb the suture and the thread will be discharged out of the skin, at this time, you will see a black thread, which will fall off by itself. In addition, when the incision was closed with non-absorbable sutures, the threads were not removed cleanly during suture removal, and black threads will appear after the incision has healed. If the local non-absorbable thread is used after the incision is healed, you need to go to the hospital in time to remove the black thread, which can avoid the local foreign body induced inflammatory reaction. It is recommended that the localized black threads after incision healing should seek medical treatment promptly, and the doctor will choose appropriate measures according to the cause of the black threads. In addition, the local black threads should be kept clean and dry, and the wound should be sterilized with iodine or alcohol every day to avoid infection.