As endogenous nanovesicles, exosomes promote cellular communication and exchange by transporting intracellular proteins, nucleic acids and lipids, and are ideal drug delivery vehicles due to their good biocompatibility, high stability and specific targeting to tissues and cells. In addition, the application mechanism of exosomes in the diagnosis and treatment of neurological diseases, tumors, and cardiovascular diseases has also been thoroughly studied. In this paper, we reviewed the application of exosomes in targeted drug delivery and the mechanism study of exosomes in the treatment of diseases, aiming to provide theoretical guidance for future research and clinical application.