Abstract: Exosomes are involved in cell communication and other processes,with the characteristics of low toxicity,low immunogenicity,high biocompatibility,and capability of crossing the blood-brain barrier.However,exosomes need to be modified to avoid rapid clearance by the immune system,enhance target cell specificity,and improve intracellular delivery efficiency.In recent years,transfection of proteins or oligonucleotides into exosomes by "cell engineering" or modification of ligands by "exosome engineering" can enhance the role of the drug carrier system of exosomes.In addition,functionalized exosome ligands can slow exosome clearance and transmembrane efficiency.This article reviews the progress of exosome modification methods and explores improved strategies for functionalized exosomes.