Abstract: Peptide drugs have been one of the important fields of new drug research because of their small molecular weight, high biological activity, easy modification and large-scale preparation. In addition to being directly used as drug candidates or precursors for small molecule drug design, peptides have a very important application in drug development, i.e. as targeting molecules. The specific binding of the polypeptide-directed molecule to the target of the lesion site can mediate more efficient accumulation of the small molecule drug or drug delivery system in the target site, thereby achieving high efficiency and low toxicity. In this paper, the source, optimization and application progress of peptides as targeting molecules in recent years are reviewed so as to provide reference for related researches.