Abstract: Exosomes are disk-shaped vesicles with a diameter of 40-100 nm, which are composed of natural lipid bilayers. Most cells can produce exosomes, which play an important role in physiological and pathological processes, affecting signal pathways, intercellular communication, tumor progression and molecular metastasis. Exosomes are characterized by low immunogenicity, good natural stability, long half-life, high delivery efficiency, and the ability to cross the blood-brain barrier, which can be used as a good carrier for drug delivery. This review focuses on the research progress of exosomes as drug delivery systems in the treatment of brain diseases, such as central nervous system degenerative diseases, brain tumors and cerebrovascular diseases and so on.