Red tongue with thin coating can be seen in the initial stage of exogenous symptoms (mainly manifested as respiratory symptoms after feeling external evil), or due to Yin deficiency and internal heat, and can also be seen in normal people. The red tongue is usually the main heat evidence, and the thin tongue coating is mostly for the initial stage of the disease or indicates that the disease is mild. Normal people’s tongue is mostly light red tongue with thin white moss, red tongue with thin moss is also seen in normal people. If seen in the state of disease, it is mostly for the beginning of external symptoms, for the feeling of heat at the beginning or the performance of heat; such as Yin deficiency, can also be seen in the tongue red moss thin or less moss or even no moss of the performance of the deficiency of heat. In addition to reacting to the nature of the disease, red tongue and thin moss can also react to the state of the disease, such as red tongue and thick moss gradually turned into red tongue and thin moss, it is mostly for the performance of the internal heat gradually recede. If the tongue is light red or the tongue white gradually becomes red, then it is mostly a manifestation of the disease evil into the inner heat. It is necessary to analyze the evidence with the specific situation.