Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) is a progressive syndrome with a high incidence and mortality rate. Apoptosis is a very important pathological feature of ALI. Recently, more and more researches on mircoRNAs are involved in the regulation of proliferation and apoptosis of cancer cells. However, the functions of microRNAs in ALI remain unknown. In this study, PCR array and qRT-PCR were used to investigate microRNA profiles and miR-181a regulates apoptosis induced by LPS. Then, we predict the potential target gene of miR-181a is BCL-2 by bioinformatics methods, and validate it using luciferase reporter gene assays. Finally, the effect of miR-181a on apoptosis was investigated in ALI animal model and cell model induced by LPS. Inhibition expression of miR-181a can significantly reduce LPS-induced acute lung injury in mice and A549 cells. Therefore, we suggest that MiR-181a inhibition protects mice from LPS-induced acute lung injury by targeting Bcl-2.