Objective To explore and analyze the effects of ω-3 polyunsaturated fatty acid(PUFA)on oxidative stress and Toll like receptor-4(TLR4)and tumor necrosis factor alpha(TNF-α)in rats with acute lung injury(ALI)induced by lipopolysaccharide (LPS).Methods 120 healthy adult Wistar rats(clean grade;weight,180-240 g)were randomly divided into control group and ob-servation group,60 rats in each group,rats in the control group were randomly divided into untreated group,6 h group(LPS injec-tion),and 24 h group(LPS injection),20 rats in each group.The rats in the observation group were randomly divided into untreated group,6h group(PUFA+LPS injection),and 24 h group(PUFA+LPS injection),20 rats in each group.The relative expression of Superoxide Dismutase(SOD)before treatment,6 h after treatment and 24 h after treatment,Malondialdehyde(MDA),intercellular cell adhesion molecule-1(ICAM-1),TNF-α,and TLR4 in two groups were observed.Results The difference of SOD levels before and after treatment in the two groups of rats was statistically significant(P<0.05),the difference of SOD levels before treatment in the two groups of rats was not statistically significant(P> 0.05).As the processing time went on,the level of SOD in the two groups of rats decreased,but the decrease of the rats in the observation group was lower than that of the control group,and the difference was statistically significant(P<0.05),the difference of MDA level before and after treatment in two groups of rats was statistically significant(P<0.05).As the processing time went on,The level of MDA in the two groups of rats increased,but the increase of the rats in the observation group was significantly lower than that of the control group,and the difference was statistical-ly significant(P<0.05).The difference of ICAM-1 level before and after treatment in the two groups of rats was statistically signif-icant(P<0.05).As the processing time went on,the levels of ICAM-1 and TNF-alpha in the two groups increased,but the increase of the rats in the observation group was significantly lower than that in the control group,the difference was statistically significant (P<0.05).The relative expression of TLR4 in the lung tissue of the observation group was significantly lower than that of the control group(P<0.05).Conclusion PUFA could effectively reduce the oxidative stress and inflammation in ALI rats induced by LPS,which may contribute to the treatment of ALI.