Natural moisture-keeping & skin-nurturing functions. There are many hydrophilic gene located at the surface of stereo molecular structure of silk peptide, which confirmed that the silk peptide is the natural moisture-adjusting factor which has the excellent moisture-keeping function. There are testings indicated that under the conditions of 27 ºC (of temperature), 86%RH (of relative humidity), and 12 hours (of hygroscopic time), the hygroscopic rate of 2.5% density of silk peptide lipuid is epuivalent to the one of 48% density of glycerol. Other testings indicate that since the silk peptide has the strongest permeability, it will permeate to the skin cuticle to play the moisture-keeping function after it being smeared on the skin for about ten seconds, because the little molecular silk peptide after passing through the skin cuticle, is linked with the skin epithelial cell, and is absorbed by it as the nurture materials to join and to promote metabolism, so as to give the skin gloss, nutriment, softness & elasticity.