A red tongue with little moss is often seen in cases of yin deficiency and fire exuberance (deficiency of yin essence in the body, resulting in hyperactivity of deficiency fire), and heat illnesses that injure the yin. 1. Excessive Yin deficiency and fire: the Yin fluid in the body is reduced by many factors, which makes it difficult to restrain the Yang energy in the body, and thus the tongue moss manifestation of the exuberant rise of the deficiency fire. The patient is often accompanied by emaciation, dry mouth and throat, five heart-heat (heat in the heart of the hands and feet, and consciously hot heart and chest), night sweating (sweating abnormally after going to sleep, and waking up after sweating stops) and other manifestations. 2. Injury of Yin by Heat Disease: The patient feels the evil of heat and poison, which gradually injures the fluid and depletes it, and in the later stage, the symptom of Yin deficiency will appear, and the red tongue with little moss is one of its manifestations. Therefore, patients with red tongue and little moss are often considered to be related to yin deficiency and heat illness, and it is recommended that patients with symptoms should choose appropriate treatment programs under the guidance of a professional physician in order to prevent progressive aggravation of the condition.