Abstract: Acute lung injury (ALI) is a clinically common critical disease with various treatment methods. Stem cell has drawn great attention for excellent performance in treatment of ALI. However, due to its high apoptosis rate, the further clinical application of stem cell is restricted. Exosomes are a kind of extracellular vesicles secreted by cells, which play important role in injury repair with further research about exosomes. This article reviews current situation, brief introduction to exosomes, repair effects of exosomes on ALI, and the potential signal pathway.