Mouth ulcers, also known as mouth sores, have the following TCM arguments: The first point, accumulated heat in the spleen and stomach, can be treated by clearing the stomach. The second point, inflammation of heart fire, can be treated by applying Guiding Chi San and Diarrhea Heart Tang. The third point, liver stagnation and qi stagnation, can be treated by applying Danjian Yi Yao Wan. The fourth point, Yin deficiency and fire, can be treated with Zhi Bai Di Huang Wan. The fifth point, deficiency of spleen and dampness, can be treated with Seven Flavors of Atractylodes. The sixth point, deficiency of spleen and kidney yang, can be treated with Annex Gui Ba Wei Tang. Clinically, for the treatment of mouth ulcers, it is necessary to choose different herbal formulas to regulate the treatment according to different types of evidence and make appropriate additions and subtractions under the doctor’s identification, so that the complicated condition can be significantly improved. Clinically, for the treatment of mouth ulcers, attention should also be paid to the regulation of diet and exercise.