The process of repairing an old fourth-degree perineal laceration can be divided into exposing the wound, disinfecting the wound, closing the wound layer by layer and postoperative care. 1. Exposure of the wound: the vagina should be filled with a gauze pad with a tail, and the upper and lower lobes of the vagina should be opened with a pulling hook to expose the laceration wound. 2. Wound disinfection: the wound should be thoroughly cleaned with iodophor or other disinfectant. 3. Layer by layer suture: When the rectal wall is torn, the rectal plasma muscle layer can be closed with interrupted mattress suture and the submucosa of rectum can be closed with interrupted U-shaped suture, and the severed end of anal sphincter, anus raphe muscle, perineum deep and superficial transverse muscle and bulbocavernosus muscle can be closed with interrupted suture, and finally the mucosa of vagina, subcutaneous tissues and skin can be closed with layer by layer suture. 4. Postoperative care: after the operation, you need to eat semi-liquid food, reduce the frequency of bowel movements, pay attention to wound cleaning, generally five days after the operation, the stitches can be removed. In daily life, you should pay attention to rest, appropriate exercise, keep the local skin clean, if you have symptoms of physical discomfort, you should go to the hospital in time to consult a specialist for guidance.