The etiology of repeated oral ulcers is more complex, and there are differences in personal constitution, the common causes are as follows: 1, the body immune differences: including cellular differences, fluid differences and autoimmune differences; 2, the family genetic differences: the characteristics of family heredity, in the performance of the immediate family members of the more obvious; 3, the systemic differences: the main manifestation of the digestive system, as well as the endocrine system, mental factors, etc.; 4, the infectious factors: the digestive duodenal part of the helicobacter pylori contact is the main; 5, the environmental factors: including poor living habits, mental stress, etc..