OBJECTIVE： To study the effects of spirulina kinase （SPK） on the vascular endothelial function of model rats with atherosclerosis. METHODS： 60 rats were randomly divided into normal control group （distilled water）， model group （distilled water）， positive control group （simvastatin， 0.005 g/kg） and SPK low-dose， medium-dose， high-dose groups （80， 160， 320 U/kg）. Except for normal control group， rats in other groups were induced for model of atherosclerosis. All groups were intragastrically administrated relevant medicines at the same time， once a day for consecutive 12 weeks. Total cholesterol （TC）， triglyceride （TG）， low density lipoprotein cholesterol （LDL-C）， high density lipoprotein cholesterol （HDL-C）， interleukin-6 （IL-6）， tumor necrosis factor-α （TNF-α） contents in serum of rats were measured. And the changes of thoracic aortic endothelium morphology were observed by HE staining. RESULTS： Compared with normal control group， TC， TG， LDL-C， IL-6， TNF-α contents in serum of rats in model group were increased （P＜0.01）， HDL-C content in serum was decreased （P＜0.01）； vascular endothelial cells fell off， intimal proliferation projected into the lumen， smooth muscle cell proliferated and disordered， medium film elastic fiber disintegrated and fractured. Compared with model group， TC， TG， LDL-C， IL-6， TNF-α contents in serum of rats in administration groups were decreased （P＜0.05 or P＜0.01）， HDL-C content in positive control group and SPK medium-dose， high-dose groups was increased （P＜0.05）. Vascular endothelial cell morphology was improved significantly in administration groups， in which， vascular endothelial cells were structurally intact in SPK medium-dose， high-dose groups， inner membrane was basically smooth； medium smooth muscle cells arranged slightly disordered in SPK medium-dose group. Compared with normal control group， there were no obvious changes. CONCLUSIONS： SPK shows obvious lipid-lowering and anti-inflammatory effects， it can protect vascular endothelial function. The mechanism may be related to reducing TC， TG， LDL-C， HDL-C， IL-6， TNF-α contents and increasing HDL-C content in serum.