Malonic acid and its derivatives are widely used in pharmaceutical, fragrance, food additives, polyester and other industries, and are important fine chemical raw materials and intermediates. Especially in the field of pharmaceutical intermediates, diethyl malonate is widely used in the synthesis of barbic acid, amino acids, vitamins B1, B2 and B6, sleeping drugs and phenylbutazone and other drugs. Diethyl malonate is an important fine chemical raw material. Because the methylene hydrogen in its molecule is easily replaced by a variety of groups, and then generates a variety of important derivatives, it is widely used in various chemical production. Fields, including food, medicine, pesticides, industrial dyes, liquid crystal materials and other industries.