Tongue diagnosis is an important part of the four diagnosis of traditional Chinese medicine（ TCM）

and the oral flora corresponding to the tongue coating has a characteristic correspondence with the changes of intestinal flora. The basis for this connection is that oral microbes are colonized in the intestine by blood or digestive tract

or by transferring the flora metabolites through the immune system. It also exists in non-digestive diseases such as nervous system diseases and cardiovascular diseases

and the essence or the microbe communicates with the host immune system and participates in metabolic processes beneficial to both the host and the microorganism. It is believed that the grasp of the relationship between the intestinal flora of the oral flora of the tongue coating reflects the disciplinary characteristics of the overall thinking of Chinese medicine. The systematic and standardized study of the sphagnum flora may provide more abundant materials for the objectification of TCM diagnostic techniques.