Abstract: Extracellular vesicles （EV） are a variety of membrane vesicles consisting of lipid bilayers released by cells in a resting or stress state. EV can be divided into different subgroups, such as exosomes, microvesicles and apoptotic bodies according to the formation mode, size or function. It is difficult to isolate EV because of its small volume and low density. Moreover, the physical and chemical properties of EV vary after the isolation by different methods. Currently, insufficient understanding of EV and lack of uniform criteria for identification are the main factors restricting the research and translational application of EV. In this article, the classification, biogenesis mechanism and characteristics of EV, as well as the isolation and identification methods of EV were reviewed to provide reference for EV research.