Peptide coupling agents are chemical reagents used to promote the connection between amino acids or polypeptides. In the process of peptide synthesis, peptide coupling agents can effectively react the carboxyl group of an amino acid with the amino group of another amino acid to form a peptide bond. By using these coupling agents, the efficiency and selectivity of the reaction can be improved and the generation of by-products can be reduced. They are used in the synthesis of targeted drugs to enhance the stability and biological activity of drugs.