Abstract: Objective To study the effect and mechanism of miR-146a in atherosclerotic plaque． Methods Rat monocyte macrophages were transfected with agom ir-146a (miR-146a mim ic) and antagomir-146a (miR-146a inhibitor), and exposed to ox-LDL after transfection． Macrophages were stained with oil red O and sem i-quantitative analysis were used to evaluate the effect of miR-146a on lipid accumulation． Western blot was employed to detect the expression of CEH, ABCA1 and ABCG1． Results Western Blot showed that the expression of CEH signif cantly decreased in miR-146a mimics, while the expression of ABCA1 and ABCG1 in miR-146a inhibitor transfection group increased much more than they were in the control group and miR-146a mim ic transfection group． Oil Red O staining showed that the positive cells ratios in miR-146a mim ic transfection group and control group and miR-146a inhibitor transfected group were 82．1%±3．1%, 73．2%±0．162% and 16．25%±2．1% respectively． Conclusion miR-146a can inhibit the expression of CEH in rat peripheral blood mononuclear cells and hinder cholesterol effux, thus resulting in atherosclerotic plaque formation．