In drug development research, in order to increase the half-life of peptide drugs in vivo, reduce the immunogenicity, and increase the water solubility of the drugs, activated PEG was chemically coupled to the peptide drugs. The study of PEG modification of peptide compounds is later than related studies of proteins, and some progress has been made in recent years. For example, the half-life and biological activity of PEG-modified products of calcitonin and epidermal growth factor are significantly higher than those of prototype drugs.