It is a compound with a very high quantum efficiency, in the order of 1 million to 100,000 parts, which can effectively whiten natural or white substrates (such as textiles, paper, plastics, coatings). It can absorb the violet light with a wavelength of 340-380nm and emit blue light with a wavelength of 400-450nm, which can effectively make up for the yellowing caused by the blue light defect of white materials. It can improve the whiteness and brightness of the white material. The fluorescent whitening agent itself is colorless or light yellow (green) color, and is widely used in papermaking, textile, synthetic detergent, plastics, coatings and other industries at home and abroad. There are 15 basic structural types and nearly 400 chemical structures of fluorescent whitening agents that have been industrialized.