Polyethylene glycol is one of the most commonly used synthetic macromolecular polymers for modifying small molecule drugs, peptides, proteins or Nano-drug delivery systems to improve their water solubility, biocompatibility and stability.Block copolymers containing PEG have been widely used in Nano-drug delivery systems such as solid lipid nanoparticles, polymeric nanoparticles, polymeric micelles and liposomes. To date, although numerous PEGylated Nano-drug delivery systems have been developed, only a few have been approved for clinical application.Poor safety and effectivity are important reasons for the high failure of Nano-drug delivery systems clinical trials. These factors are not only related to the loaded drugs and released drugs, but also related to the nanocarriers. Therefore, investigating the in vivo spatiotemporal fate of block copolymers containing PEG used in Nano-drug delivery systems is necessary and important for evaluating their safety, efficacy and toxicity. In this article, we will review the information that has been reported about the absorption, distribution, metabolism and excretion of block copolymers containing PEG. We believe this review is helpful to understand the biological fate of block copolymers containing PEG.