Exosomes belong to microvesicle structures widely distributed in many body fluids secreted by a variety of living cells, which can carry biological information molecules such as nucleic acids, proteins and lipids derived from parental cells, being the communication carriers among cells. Exosomes play a critical role in cancer progression and participate in tumor cell proliferation, tumor migration, immune escape and angiogenesis. In hematologic system, exosomes involve in the crosstalk between leukemia cells and the surrounding environment, promote the formation of leukemia microenvironment and act as immunomodulators, which will be a potential direction for its therapeutic research. This article reviews the biological characteristics of exosomes and their roles in leukemic tumor microenvironment and immune regulation.