Tremella Polysaccharide is a new type of plant derived high efficiency humectant extracted from Tremella fuciformis. It is a kind of water soluble polymer, the average molecular weight is over one million Da., and the molecular structure backbone is Mannan made up by alpha (1-3) - glycosidic bond composition, and the branched chain by glucuronic acid, xylose and fucose etc., the active part is common structural part of alpha (1-3) - mannan.