Tongue moss is a layer of moss on the surface of the tongue, which is caused by the vaporization of spleen and stomach qi on the stomach and yin. Observation of tongue moss should observe the two aspects of moss quality and moss color. Normal tongue moss should be thin, white and even, with moderate wetness and dryness. The quality of the tongue moss should be observed in terms of its thickness, moistness and dryness. Thick and thin moss can reflect the depth of the disease and the evil spirits, moist and dry moss can reflect the body’s fluid surplus and deficit and the transmission and distribution of the situation. There are three main colors of tongue moss: white, yellow and gray-black. White moss can be called normal tongue moss, can also be seen in the surface evidence, cold evidence, wet evidence. Yellow moss can be used for internal symptoms and heat symptoms. Gray and black moss can be the main evil heat, Yin cold or phlegm and dampness for a long time. When the tongue coating is abnormal, you can consult a doctor in time to avoid delaying the condition.