Recurrent oral ulcers may be related to a variety of factors such as immunity, genetics, systemic diseases, and the environment. 1. Immune factors: including auto-cellular immunity, humoral immunity and other abnormalities of the immune system. 2. Genetic factors: for example, recurrent aphthous ulcers, the development of which has a genetic predisposition. 3. Systemic disease factors: may be related to gastric ulcer, duodenal ulcer and other diseases. 4. Environmental factors: life and work environment and mental stress, anxiety and other psychological environment and other factors can also affect the occurrence of oral ulcers. The occurrence of oral ulcers is generally considered to be the result of multiple factors, usually should pay attention to the regularity of life and so on. If persistent mouth ulcers occur, it may also be a manifestation of other diseases, such as leukemia. It is therefore recommended that people with recurrent mouth ulcers should seek medical attention.