Aim To study the influence of omentin on the expression of collagen Ⅰ/Ⅳin the human aortic smooth muscle cells subjected to oxidative stress. Methods Human aortic smooth muscle cells were cultured in vitro.When cell density reached above 90%, cells were randomly divided into 5 groups:control group, oxidative stress group, omentin group, ERK(extracellular regulated protein kinases) inhibitor group and p38MAPK(p38 mitogen-activated protein kinases) inhibitor group. Among them, the control group did not receive any treatment, oxidative stress group were treated with tert-butyl hydroperoxide(t-BHP, 87.1 μmol/L) to simulate the state of oxidative stress; omentin group were treated,except for 87.1 μmol/L t-BHP,with 600 μg/L omentin; except for t-BHP(87.1 μmol/L) and omentin(600 μg/L),ERK inhibitors(PD98059,60 μmol/L) and p38MAPK inhibitors(SB203580,100 μmol/L )were used in ERK inhibitor group and p38MAPK inhibitor group respectively. The expression of collagen Ⅰ/Ⅳ were detected by Western blot hybridization. Results MMT method was used to screen the optimal concentration and the best action time of t-BHP.(1)The optimal concentration was 87.1 μmol/L;(2)Compared with the control group, the expression of collagen Ⅰ/Ⅳin human aortic smooth muscle cells in oxidative stress group decreased significantly(P<0.01);(3)Compared with the oxidative stress group, the expression of type Ⅰ/Ⅳcollagen in human aortic smooth muscle cells increased significantly in omentin group(P<0.01);(4)Compared with the omentin group, the expression of collagen Ⅰ/Ⅳin ERK inhibitor group and p38MAPK inhibitor group were decreased significantly(P<0.05). Conclusion Omentin could improve oxidative stress-induced down-regulation of Ⅰ/Ⅳcollagen in the human aortic smooth muscle cells,and probably promote the stabilization of atherosclerotic plaque through the mechanism. ERK/p38MAPK signaling pathway may be involved in omentin effect in vivo.