The inspection of tongue coating is the most direct and the most common way to diagnose and detect diseases in our clinical practice.Meanwhile,tongue coating is also the most direct external manifestation of the deficiency,excess,cold and hot state of human diseases.Generally,the greasy moss in the clinical suggests dampness-heat or phlegm turbid in human body.However,in special cases,yin deficiency and qi deficiency may also cause greasy moss.Therefore,we should know that the condition will change,and we should not be limited to fixed thinking mode.