L-Methionine is a sulfur-containing essential amino acid. In terms of chemical structure, its molecular structure contains an amino group and a carboxyl group, along with a unique sulfur atom. Regarding physiological functions, it is of great significance to human health. It participates in protein synthesis and is an important component of many proteins, playing an indispensable role in maintaining normal physiological metabolism, tissue growth, and repair in the human body. It is also crucial in the field of animal nutrition. It is a common additive in animal feed, which can improve the growth performance and immunity of animals. In the pharmaceutical industry, it can be used to prepare amino acid infusions. Moreover, it finds applications in the cosmetics industry, being used in skin and hair care products to help maintain the health of the skin and hair.