Extracellular vesicles are a group of endogenous nano-vesicles that carry host- and pathogen-derived proteins, nucleic acids and lipids. They can be produced by most types of cells and some pathogens, and play important roles in cell-to-cell communication. After pathogen infection, extracellular vesicles participate in the process of immune regulation by the pathophysiological changes mediated by spreading host- or pathogen-derived molecules. Here, we summarized the functions and mechanisms of extracellular vesicles in the pathogenic process of bacteria, viruses, fungi and some other pathogens, including promoting the transmission and replication of pathogens, changing the antigenicity and infectivity of pathogens through material transport, and affecting the immune response in human body.