It is well known that tongue diagnosis is a necessary and crucial part of the diagnosis of diseases in Chinese medicine. Western physicians rarely look at the patient’s tongue, which is very different from TCM. The tongue, a seemingly simple muscular organ, is composed of transverse muscles. The upper part is called “tongue surface” and the lower part is called “tongue base” in Chinese medicine. The surface of the tongue has a lingual mucosa with three types of lingual papillae: filiform papillae, fungiform papillae and contour papillae. The latter two types of tongue papillae contain taste buds, which allow the sensation of taste. In Chinese medicine, it is closely related to the heart, liver, spleen and kidney, and has meridians connected to them. Of these, the relationship with the heart is the closest. In terms of parts, the tip of the tongue belongs to the heart, the middle of the tongue to the spleen and stomach, the two sides to the liver and gallbladder, and the root of the tongue to the kidneys.