The absence of tongue coating in the middle of the tongue belongs to peeling moss, cracked tongue, map tongue, etc., which may be caused by spleen and stomach damage, spleen deficiency and blood deficiency. 1. Peeling Moss: Peeling Moss is mostly caused by the heavy burden on the spleen and stomach due to improper diet and overfeeding, thus damaging the stomach qi. Due to the decline in the function of the spleen and stomach or the lack of stomach qi, a piece of tongue without tongue moss in the middle of the tongue is likely to occur. 2. Cracked Tongue: Cracked tongue refers to the appearance of various shapes of cracks and grooves on the tongue, and there is no tongue coating in the grooves and grooves, which is mostly caused by blood deficiency, spleen deficiency and dampness, etc. The symptom is that there is a piece of tongue without tongue coating in the middle. Its symptoms are a piece of tongue in the middle of the tongue without tongue moss, irregular grooves and cracks. 3. Map Tongue: Map Tongue refers to a large irregular flaking of tongue moss, with clear boundaries and a shape similar to that of a map, which is mostly caused by deficiency of Yin and Blood, because most of the flaking part of the tongue moss is in the middle of the tongue body, which may lead to a piece of tongue moss in the middle of the tongue without the tongue moss phenomenon. When the patient has a piece of tongue without tongue moss in the middle of the tongue, it is recommended to go to a regular dental hospital in time to find out the cause of the disease, under the guidance of the doctor to actively cooperate with the treatment.