Green tongue may be caused by Rhizopus spores containing melanin or because of excessive smoking, as well as the use of oral thai mouthwash or consumption of pickled pickles, etc. Through observation of tongue bacterial culture and bacterial quantification, temperature and pH of the tongue, fluorescence phenomenon, microscopic examination of the tongue and pathological biopsy, it is found that the color of the tongue is related to the color of the dominant colony, and may also be related to smoking, drugs, food, saliva pH, etc. Therefore, patients who have a green tongue may look for the above-mentioned causes. In addition, TCM believes that different colors of the tongue moss reflect different symptoms, and black moss is the main internal symptom, which is mostly seen in those who are more seriously ill. In addition, if the patient uses some drugs containing pigment, it can also change the color of the tongue moss and make it green. If the tongue is green, you can go to the stomatology department of the regular hospital for examination as soon as possible.