Exosomes are small membrane vesicles secreted into extracellular matrix after the fusion of intracellular multivesicular bodies and cell membrane and their diameters are between 30-100 nm. Exosomes contain mRNAs, miRNAs, and proteins of source cells that can represent biological information of source cells, so they are potential biological markers. Effects of exosomes on signal transduction, inducing anti-tumor responses, and immunologic tolerance responses, etc. become research hotspots in recent years and have been used in new treatments. The urinary exosomes are closely related to the physiological functions and diseases of kidneys. However, the research in this field is only in early stages. This review aims to summarize the research developments of biological characters, physiological functions, separation and purification of exosomes, and their effects as biological markers and treatment values for kidney diseases.