There is a hole inside the child’s cheek which is caused by normal physiological structure or mouth ulcer. 1. Normal physiological structure: there is an opening of parotid duct in the buccal mucosa corresponding to the crown of maxillary second molar (i.e., the inner side of parotid), which is a sunken structure that is similar to a hole-like tissue; the opening of the parotid duct usually has no clinical symptom, and does not require special treatment. 2. Mouth ulcers: recurrent mouth ulcers can also produce depressed lesions, in the form of deep pits; and accompanied by pain, redness and swelling and other symptoms; must be treated symptomatically, such as anti-inflammatory and pain relief treatment, or under the guidance of the doctor to use cotrimoxazole gargle or rehabilitation of new liquid to promote the healing of mouth ulcers. Children with a hole in their cheeks are advised to seek medical attention for a clear diagnosis and symptomatic treatment to avoid delaying the condition.