The causes of recurrent mouth ulcers are more, but not very precise, generally related to staying up late, oral hygiene, nutritional imbalance, immune function. Mouth ulcers are a kind of self-healing and recurrent disease that occurs on the oral mucosa. Recurrent mouth ulcers may be caused by staying up late late; not paying attention to oral hygiene, having a lot of plaque, tobacco stains, etc.; unbalanced nutrition such as lack of vitamins; and abnormalities in immune function such as T-cell or B-cell abnormality. Clinical advice for patients with recurrent mouth ulcers is to eat more fruits and vegetables, keep bowel movement smooth, reduce stress, stay up late, avoid oral bites, improve immunity, and if it doesn’t improve, we recommend that they go to the dentist in a timely manner.