Acute lung injury (ALI) is a common and complex disease characterized by severe pulmonary inflammation. As a new type of gene regulator, microRNA (miRNA) plays vital roles in a wide range of human disorders and diseases, including ALI. During the process of lung injury and repair, certain kinds of miRNA express abnormally and can modulate inflammation pathways as well as immune response by affecting expressions of target genes. Therefore, miRNA can serve as biological markers for ALI. This paper reviews the effects of miRNA on ALI.