Abstract： Objective To explore the mechanism and effect of miR-146a on alveolar macrophages and to observe the changes of miR-146a expression in the LPS-induced alveolar macrophages. Method NR8383 alveolar macrophages were divided into LPS-stimulated group and control group, and the cells of former group were treated with LPS ( 1 μg/mL) and then incubated for 3 h, 6 h and 12 h, respectively. The level of TNF-α in the supernatant of cells was assayed by using enzyme-linked immunosorbent assay (ELISA), and the expression of miR-146a of cells was detected by using Real-Time PCR (TaqMan probe).Statistical analysis carried out by using SPSS 13.0 software package in which One-way ANOVA and Student's t-test were used. Results Compared with control group, the levels of TNF-α in the supernatant of cells were significantly increased 3 h, 6 h and 12 h after LPS challenge (P ＜ 0.01 ). The expression of miR-146a increased 6 h and 12 h after LPS stimulation in NR8383 cells( P ＜0.01 ), and it had an upward tendency.Conclusions The expression of miR-146a in alveolar macrophages increases after LPS-stimulation. It hints miR-146a may be involved in the regulation of the inflammatory responses produced by alveolar macrophages.