Black tongue moss can appear in two cases: extreme cold, extreme heat, dyed moss can also lead to, as follows: 1. If it is extremely cold, the moss is on a greasy basis, looking like a layer of greasy mud black, generally on the cool side, insufficient Yang Qi, excessive accumulation of dampness leading to black moss; 2. If it is extremely hot, it is black dry moss, thicker tongue moss, but very dry case appears black moss, black moss accompanied by yellowish brown moss underneath appears. The surface is black, it is the manifestation of polar heat evidence from hot dry heat to deep heat. In short, black tongue moss needs to be actively dealt with, as long as the distinction is not dyed moss, it should be dealt with by medication for extreme heat or extreme cold, general food adjustment is no longer in place. Pay attention to other signs of the body when administering medication. In addition to the distinction between the quality of the moss, pay attention to the patient’s own physical sensation, pulse sensation and physical condition to distinguish between hot and cold.