White and thick tongue coating is caused by phlegm and dampness in the body, which leads to the deficiency of spleen and stomach yang, and cannot transport and transform phlegm, water and dampness. The color of the tongue coating reflects the changes of cold, heat, dryness and dampness in the body. Yellow moss is the manifestation of heat and dryness; white moss is the manifestation of cold and dampness. The texture and shape of the tongue coating reflect the changes of phlegm, food, water and dampness. Thick moss is a tangible and turbid evil, such as phlegm and dampness, etc. Thick and greasy moss is mainly for food accumulation (indigestion of food and accumulation in the stomach) and phlegm and dampness; and little moss is for insufficient fluids. Therefore, white and thick tongue coating may be caused by excessive cold and dampness in the body, leading to Yang deficiency in the spleen and stomach, or it may be caused by overeating fatty, sweet, thick, greasy or sweet food, which damages the spleen and stomach and leads to the spleen and stomach not being able to transport and transform the tangible evils. White and thick tongue coating can be caused by a variety of reasons, it is recommended to identify the cause of the disease under the guidance of a professional doctor, and then the right treatment.