AIM:To investigate the SD rats which were used to establish hyperoxia-induced retinopathy of prematurity(ROP) model,providing experimental basis to study the pathogenesis and treatment of disease.METHODS:Twenty-four newborn SD rats were divided into two groups,one group were placed in IPR-2 mice separate package where given hyperoxia [(75±2)% O2] from postnatal day 1 to 7(P1-7) and after then,exposed to room air(P8-14),the other group placed in room air(P1-14).At P7,P14,retinal flatmounts were obtained to study the retinal vascular pattern;at P14,the eye-tissue-sections were obtained and stained with hematoxylin-eosin to analyze the extraretinal neovascularization;stained immunohistochemically to evaluate the retinal expression of the vascular endothelial growth factor(VEGF),CD34 protein under light microscopy.RESULTS:Retinal flatmounts:A large number of the capillary-free area and neovascularization were observed in experimental group,which was more than that in control group.Tissue-sections stained with hematoxylin-eosin:The number of vascular cell nuclei in experimental group was obviously more than that in control group.Immunohistochemical study:CD34 and VEGF protein expressed positive in the extraretinal vascular cells anterior to the internal limiting membrane.VEGF semi-determination showed the mean gray scale values was lower in experimental group than that in control group,but the area density values in experimental group was higher than that in control group.The development condition of rats was normal.CONCLUSION:The SD rats with the hyperoxia-induced animal model of ROP can successfully produce retinal neovascularization,and the model can be a reliable animal model as exploring mechanisms and treatment of disease.