Cysteine is an essential amino acid for the human body.l-cysteine whitening, It maintains the activity of an important sulfylase in the production of keratin in skin proteins, and supplements sulfur groups to maintain the normal metabolism of the skin and regulate the production of pigment cells in the lowest layer of the epidermis. The underlying melanin is an ideal natural whitening cosmetic. It can remove the melanin of the skin itself, change the nature of the skin itself, make the skin whiten naturally,l-cysteine whitening, and has a keratolytic effect.