Mouth ulcers belong to the category of “mouth sores” in traditional Chinese medicine (TCM), which may be caused by real or imaginary fire. Chinese medicine believes that the pathogenesis of mouth sores is based on the disorders of the heart, spleen and kidneys. Solid heat in the upper focus is mostly accumulated heat in the heart and spleen, yin fire in the lower focus is a deficiency of yin and yin in the kidneys (deficiency of yin and essence in the body, resulting in hyperactive fire), and deficiency of cold in the middle focus is mostly a deficiency of yang in the spleen and kidneys (deficiency of yang qi in the spleen and kidneys). 1. Accumulated heat in the heart and spleen: ulcers of the oral muscular membrane, redness and swelling around the periphery, obvious burning pain, especially when eating or talking, thirst, insomnia and heartburn, constipation, short yellow urine. The tongue is red, the moss is yellow or greasy, and the pulse is numberless. It can be taken with the addition and subtraction of Liang Diaphragm San. 2. Yin deficiency and fire exuberance: mouth ulcers are few in number, with little peripheral redness and swelling, and mild pain, but they may persist. Heat in the hands and feet, insomnia, dryness of the mouth and tongue, no desire to drink. The tongue is red with little moss, and the pulse is fine (the pulse becomes narrower, thinner and faster). You can take Zhi Bai Di Huang Tang plus subtractions. 3. Spleen and kidney yang deficiency: Mouth sores are mildly painful, white or dark in color, with reddish or non-reddish periphery, and difficult to heal for a long time. Tiredness (fatigue), pallor, coldness and pain in the waist and knees or below the abdomen, long and clear urine, dullness (no appetite, less food), and loose stools (thin and unformed feces). The tongue is pale, the moss is white, and the pulse is sluggish. One can take the additional subtraction of Radix Polygoni Multiflori Tang. If mouth ulcers occur, it is recommended that scientific treatment be carried out under the guidance of a doctor.