Anal fistula is usually caused by perianal abscess festering on its own, or the wound does not heal for a long time after incision and drainage, forming the external orifice of anal fistula. The clinical manifestation is that a small amount of pus repeatedly flows out from the external orifice of fistula, polluting underwear, and sometimes pus irritates perianal skin and has itching feeling. If the external orifice is temporarily closed, pus accumulates, and there is swelling and swelling locally, the closed external orifice can be punctured again, or another new external orifice can be formed by puncturing nearby, and so on, and multiple external orifices can be formed and communicated with each other. Patients should avoid spicy food, such as wine, hot pot, barbecue, etc., which will aggravate the condition. Also, avoiding standing and sitting for a long time will aggravate the condition. It is suggested to keep the stool unobstructed, change underwear frequently and eat more crude fiber vegetables and fruits. The treatment is to use Fucaotang Xiaozhi gel developed by pure Chinese medicine, which can be cured after a period of time.