1, the normal health of the human skin base color is determined by the physiological production of basic melanin and other factors, accounting for about 18% of each, that is, usually called the composition of the skin color. The so-called “yellow race”, that is, the basic color of the skin is yellow color. The “individual differences” are caused by genetics, gender, growth period, and the level of hormone secretion in the body. The degree of melanin deposition is determined by the amount of melanin. The rate of influence of basic pigment on skin color accounts for about 18% of the total factors affecting skin color (i.e., “natural genetic and basic environmental factors). 2, darkening ultraviolet UVA (320-400nm) caused by the melanin increase in skin deepening darkening about 55% of the skin darkening factors. A whole summer has passed, our skin has also become darker to varying degrees; this is the sunlight exposure in the darkening ultraviolet (UVA band 320-400nm ultraviolet, especially 320nm, 340nm, 360nm, 380nm ultraviolet also known as “darkening UV”) induced skin The result is an increase in the amount of melanin produced by melanocytes. The rate of effect of melanogenic UVB on skin color accounts for about 55% of the total factors affecting skin color (i.e., “environmental factors”). 3, melanin accumulation (deposition) to produce pigmentation accounts for about 15% of the skin darkening factors, the degree of melanin deposition is determined by the amount of melanin content and individual differences, and excessive deposition of melanin and reach a certain pigment “concentration” and have a certain density on the skin is easy to form pigmentation, etc.. The influence rate of melanin accumulation on skin color accounts for about 15% of the overall factors affecting skin color (i.e. “individual factors”). 4.The increase of melanin caused by endogenous hormone secretion level and exogenous hormone secretion, drugs, trauma, environmental pollution, etc. accounts for about 7% of the total factors affecting skin color (i.e. “physiological or pathological factors”). 5, other factors caused by increased skin pigmentation accounted for about 5% of the skin darkening factors.