Preauricular fistula is a congenital malformation of the ear that results from the embryonic underdevelopment or fusion of the first and second gill arches, and is often found after birth as a small hole in the ear screen that spills a yellow discharge when squeezed. Patients generally do not require any treatment if there are no adverse triggers. If water enters the ear by repeatedly squeezing the area, it can lead to local infection, and the patient will have redness and swelling of the skin at the ear screen, and purulent secretions can ooze out when squeezed. In this case, the patient first needs to go to the hospital for incision and drainage to drain the pus, and local flushing with metronidazole injection two times a day. At the same time, the patient needs to take oral anti-inflammatory drugs to control the infection, and when the infection is under control, surgery is needed to remove the fistula, the fistula and the blind end to avoid post-operative recurrence.