A baby born with a small hole in the side of the ear belongs to a congenital preauricular fistula, which is a relatively common congenital condition. In terms of diagnosis, it is usually clear directly through the clinical experience of the doctor and the clinical symptoms of the patient. In terms of treatment, if the preauricular fistula is relatively stable, without redness, swelling or pain, no special treatment is needed, but the area needs to be kept dry to avoid acute infection and inflammation. If infection and inflammation have occurred, resulting in localized redness and pain, anti-infection treatment with antibiotics should be considered. If an abscess is formed, an abscess incision and drainage is also required. In case of recurrent inflammation, preauricular fistula excision is recommended and regular follow-up is needed after surgery, as some patients may have residuals that can lead to acute inflammation again.