Aim To observe the effects of different components of polyunsaturated fatty acids and their ratios on preventing atherosclerosis (As) in ApoE－/－ mice, and provide a scientific basis for rational consumption of fatty acids to prevent As. Methods The control group, the model group and three experimental oil groups were set up, and three kinds of experimental oil-made feeds were prepared according to the ratio of saturated fatty acid(SFA)∶monounsaturated fatty acid(MUFA)∶polyunsaturated fatty acid(PUFA)=0.25∶1∶1. The ratio of ω-6/ω-3PUFA in experimental oil group 1 and group 2 was designed to be 2.5∶1, and the ratio of ω-6/ω-3PUFA in experimental oil group 3 was designed to be 10∶1. The source of omega-3 PUFA in experimental oil group 1 is α-linolenic acid (ALA), and the source of omega-3 PUFA in experimental oil group 2 and experimental oil 3 is eicosapentaenoic acid (EPA) and docosahexaenoic acid. (DHA) and alpha-linolenic acid (ALA). The changes of body mass were recorded. The formation of atherosclerotic plaque was observed by oil red O staining of the entire aorta and aortic root HE staining. The hepaticmorphology and structure were observed by HE staining. The liver lipid accumulation was observed by oil red O staining. Serum levels of TG, TC, LDLC and HDLC and liver levels of TG and TC were detected by enzymatic methods. The effects of different ratio of ω-6/ω-3PUFA and different sources of ω-3 PUFA were compared. Results Compared with the model group, the three groups of experimental oil could reduce the formation of aortic As plaque (P<0.05), lower the level of TG, TC in liver (P<0.05), lower the lever of serum TG, TC, LDLC (P<0.05), and improve lipid accumulation in the liver ; Compared with the experimental oil group 1 and the experimental oil group 3, the experimental oil group 2 was more effective in inhibiting the formation of aortic As plaques (P<0.05) . The levels of TG, TC in liver were significantly decreased (P<0.05), the levels of serum TG, TC, LDLC were significantly decreased (P<0.05), the levels of serum HDLC were increased (P<0.05) in the experimental oil group 2, and thus improved liver lipid accumulation. Conclusions Reducing the intake of SFA and increasing the intake of MUFA and PUFA have anti-atherosclerosis effect. EPA, DHA, together with ALA as source of ω-3 PUFA have a stronger anti-atherosclerosis effect than ALA alone. The anti-atherosclerosis effect of low ω-6/ω-3 ratio is stronger than high ω-6/ω-3 ratio.