Objective. To detect the endothelial function of external iliac artery in rats with different stages of atherosclerosis by high-resolution ultrasound, so as to provide experimental methodological basis for evaluating the function of vascular endothelial cells by ultrasound. Methods. The animals were randomly divided into the control group (
n
=
6
) and the atherosclerosis model group (
n
=
15
). The atherosclerosis group was further divided into 4-week group, 8-week group, and 12-week group, with 5 animals in each group. After separating and grinding rat spleen, the obtained cells were cultured by density gradient centrifugation. After the cells adhered, the morphology of the cells was observed under a microscope and identified by DiI-Ac-LDL and FITC-UEA-I double staining. The activities of LDH and SOD, the contents of MDA and GSH, and the contents of NO in plasma were detected by biochemical methods. Results. The protective effect of rosanilin on brain injury in rats with acute hypobaric hypoxia and its regulation on the expression of pAkt protein; ox-LDL inhibited the proliferation activity of EPCs in a concentration-dependent manner. The expression of KLF2 and S1PR1 in HAEC can be knocked down by small interfering RNA, and knocking down KLF2 can not only downregulate the expression of S1PR1 but also downregulate HAVEN. With the development of atherosclerosis, the endothelium-dependent relaxation function and endothelium-independent relaxation function of the control group and the atherosclerosis model at 4, 8, and 12 weeks were damaged in different degrees and gradually aggravated. Conclusion. Atherosclerosis is a disease with both morphological and functional damage, and vascular endothelial function is damaged in the early stage with corresponding pathological changes. Ultrasound is an effective method to evaluate vascular endothelial function.