Melanocytes are one of the important component cells of the skin and are dendritic, through which the melanin formed in the cells is transported to the cells of the stratum corneum. It forms an epidermal unit with keratin-forming cells in a ratio of 1:36 and is present in the basal layer of the epidermis. Melanocytes form skin color by synthesizing melanin, and at the same time absorb ultraviolet light to protect the body from UV damage. The shade of skin color is determined by the amount of melanin synthesized by melanocytes, and white skin is one of the most noble beauty standards for oriental women. Melanin is a macromolecular biopigment, mainly composed of two quinone-type polymers: eumelanin (true melanin) and brown melanin. The process of skin melanin formation includes a series of complex physiological and biochemical processes such as migration of melanocytes, division and maturation of melanocytes, formation of melanosomes, transport of melanin particles and degradation of melanin. From the perspective of biochemical reactions, three basic substances are necessary for melanin formation: tyrosine is the main raw material for melanin production; tyrosinase is the main rate-limiting enzyme for the conversion of tyrosine into melanin, as a combination of copper and protein; tyrosine produces melanin under the action of tyrosinase, and the secondary action is an oxidation process that must be combined with oxygen to be converted into melanin. The currently recognized melanin formation pathway is: tyrosine → dopa → dopaquinone → dopa pigment → dihydroxyindole → ketoindole → melanin. The melanin formed is called eumelanin or true melanin, and the skin pigment is mainly composed of it. In melanin synthesis, dopaquinone can also generate brown melanin through another pathway catalyzed by glutathione or cysteine, but the efficacy of brown melanin in the skin is not known.