Prevention of mouth ulcers may require the removal of mechanical stimuli, physical and chemical stimuli, temperature stimuli, etc., as well as adequate nutritional intake, enhancement of immunity, etc. It is recommended to consult with the hospital for specifics and active prevention. 1. Correct the bad habit of biting the mucous membrane, remove the sharp tooth tip or dental calculus that can scratch the mucous membrane. 2. Try not to eat large pieces of hard food to avoid bruising the mucous membrane and developing ulcers; stay away from strong acids, alkalis and other compounds. 3. Don’t eat food that is too hot and avoid boiling water directly into the mouth. 4. Supplement nutrition to avoid the phenomenon of vitamin deficiency. 5. Improve the immunity of the whole body, often exercise to do outdoor sports, if necessary, you can supplement the immune enhancers, such as: placenta globulin, transfer factor and so on. Drugs should be used under the guidance of a physician.