PEG derivatives used as drug target by direct therapeutic PEGylation containing vehicles such as liposomes micelles, nanoparticles, dendrimers and can link together antibody-drug conjugates (ADCs) for many kinds of illnesses. PEG as the compound, also can be used to bioconjugate itself to the target, by coupling itself with the target molecule to optimize the pharmacokinetic properties of drug treatment or as a surface coating on nanoparticles to enhance systemic drug delivery. There will be more medical applications of PEG in the future. Now we focus on exploring and research how PEG can be used in peptides. PEG is widely used in biomedical applications, including drug delivery, ADC conjugation, fluorescent labeling and targeted diagnostics, oligonucleotide bioconjugation, and surface modification of proteins and peptides. As compounds, PEGs can also bioconjugate themselves to their targets, to optimize the pharmacokinetics of drug therapeutics by conjugating themselves to the target molecules, or to enhance drug delivery as a surface coating for nanoparticles. PEG will have more medical applications in the future.