Milk protein is beneficial for the health of infants and is mainly derived from bovine, sheep, goat or camel milk. High Fischer ratio peptides usually comprise two to nine amino acid residues. The ratio is computed as a molar ratio between branched-chain amino acids (BCAAs) over aromatic amino acids (AAAs) with various claimed health-promoting functions. In this Lilliput review, the classification and nutritional functions of milk proteins are discussed, the physiological functions and preparation methods of high Fischer ratio peptides are introduced, and the application of oligopeptide with unique amino acid composition and physiological functions in infant formula milk powder are reviewed. The development status of relevant industry is also summarized with future prospects. It is concluded that application of high Fischer ratio peptides prepared from milk protein in infant formula food is of great significance and requires further studies.