Abstract: Objective To study the effect of hypoxia inducible factor 2α (HIF-2α) gene knockout on atherosclerosis in mice. Methods LoxP-labeled HIF-2αmice and Mx-Cre-labeled transgenic mice were enrolled in this study. A mouse model of conditional HIF-2α gene knockout was established with the Cre/LoxP system. Mx-Cre negative wild-type mice and ApoE gene deletion (ApoE^-/-) mice served as controls. Atherosclerotic lesions of aorta were observed in the animals with HE staining 8 weeks after being fed with a high fat diet. Results Mx-Cre positive LoxP-labeled HIF-2α mice and Mx-Cre-labeled transgenic mice were produced after they mated by two passages and genotype identification. The mouse model of conditional HIF-2α gene knockout was successfully established by intra-abdominal injection with polycytidilic acid. Eight weeks after the animals were fed with a high fat diet, atherosclerotic lesions and mild intimal hyperplasia were detected in ApoE^-/- mice and wild-type mice, respectively. However, no intimal hyperplasia was detected in HIF-2α^-/- mice. Conclusion HIF-2α gene knockout can inhibit the formation of atherosclerotic lesions in mice, indicating that gene therapy for HIF-2α is a novel strategy for the prevention and treatment of atherosclerosis.