Objectives:The popuse of study is discussing the relationship between HIF-1a and neovascularization in early atherosclerosis plaques by establishing rabbit carotid atherosclerosis models,and observing the value of contrast-enhanced ultrasound in the detection of neovascularization.Methods:Forty of the male New Zealand white rabbits were randomly divided into 4 groups:group A（the blank control group）;group B（high fat diet group）;group C（silicone collar intervention and high fat diet for 14days group）;group D（silicone collar intervention and high fat diet for 14days group）,group A and group B were fed for 28 days after animal models.On the 14th days we observed the formation of atherosclerosis by carotid ultrasound detection.On the 14th days and the 28th days we detected the neovascularization in carotid atherosclerotic plaques by ultrasound-enhanced contrast,educed the peak intensity（PI） of contrast agent in plaques by time-intensity curve（TIC） and analysed the differences between them（group D）.Finally,we made the test of the level of the HIF-1α,VEGF,CD31,a-Actin,RAM-11 by immunohistochemical method in each group,found out the correlation between,at the same time analysed the correlation between PI and the expression of CD31.Results:1.There were carotid atherosclerosis plaques in group C and group D,the success rate of model-making is 100.0%.But there were not carotid atherosclerosis plaques in group A and group B.2.On the 14^th day,the group C and group D showed the neovascularization in carotid atherosclerotic plaques;On the 14^th day and 28^th day,the intensity of contrast-enhanced ultrasound showed significant statistical differences in group D.3.The mean optical density of HIF-1a,VEGF,CD31,RAM-11,a-Actin within carotid atherosclerotic plaques between group C and group D showed great statistical differences.4.The expressions of between HIF-1a and VEGF,HIF-1a and CD31, HIF-1a and RAM-11,HIF-1a and a-Actin showed high positive correlations,also the correlation between PI and the expression of CD31.Conclusions:1.During the process of atherosclerosis evolution,the neovascularization in atherosclerotic plaques has come into being in early period,and the quantity of them gradually increased accompanied the development of athersoclerosis.2.Contrast-enhanced ultrasound can detect the dynamic changes of the neovascularization within early atherosclerotic plaques.3.HIF-1a in early atherosclerosis can promote the formations of the neovascularization