Postbiotics are non-viable microorganisms and their preparations that are beneficial to the health of the host, mainly including dead cells of microorganisms, cell lysates, and cell metabolites. Systematically introducing the preparation methods of postbiotics, this paper focuses on reviewing their probiotic functional characteristics in maintaining intestinal flora balance, enhancing intestinal epithelial barrier function, enhancing immune regulation, promoting the body's metabolism, and regulating the nervous system. Additionally, this paper makes prospects for future applications of postbiotics in different fields.