Oral ulcers are a common disease of the oral mucosa that can occur in any part of the oral mucosa, with the lips, cheeks, soft palate or gums being the most common. The appearance of oral ulcers is related to the patient’s dietary habits, living environment, immune function, life and work stress, especially the dietary structure, which is among the most important influencing factors, the first consideration is the lack of vitamins in the body, followed by folic acid, iron, zinc and other trace elements. 1, vitamins: vitamins are essential for the body to maintain normal metabolism, not only to regulate the body’s metabolism, but also to promote cell growth and division. When the body lacks vitamin B2, vitamin B6 and vitamin B12 may induce mouth ulcers, of which vitamin B2 is the most common lack of the body. The skin and mucous membrane damage is the most prominent, the body’s yellow enzyme activity is weakened, so that the biological oxidation process is affected, the lesions mostly occur in the mouth, eyes and other parts, when it occurs in the mouth can be manifested as oral ulcers. Vitamin C deficiency can lead to mouth ulcers, red and swollen gums, bleeding, periodontitis, etc. Generally, oral vitamin B and vitamin C are needed for treatment; 2. Micronutrients: When the organism lacks folic acid, anemia symptoms can appear, mostly accompanied by tongue inflammation, mouth ulcers, and lip inflammation occur, and supplementation of folic acid can promote mucosal self-repair. If the patient is severely paranoid, the body is deficient in iron, zinc and other trace elements, which can easily lead to cellular immune deficiency and cause the occurrence of mouth ulcers, at this time, iron, zinc and other trace elements can be appropriately supplemented to improve the symptoms of mouth ulcers. In summary, in order to effectively reduce the stimulation of food to the oral mucosa, you should eat more fresh fruits and vegetables, replenish the vitamins, folic acid, iron, zinc and other trace elements required by the human body, try to eat food rich in a variety of nutrients and easy to digest, avoid fried food, pickled food and hot pot and other spicy and stimulating food, and develop the habit of a light diet. In addition, avoid eating foods that are too cold, too hot and too hard, so as not to aggravate the pain of the patient’s mouth ulcer. Drink less alcohol and smoke less to prevent the oral mucosa from being damaged by external factors.