Objective：To detect dynamic expression of Tenascin-X（TNX）and CD34（marker of vascular endothelial cell）and explore the correlation of both in formation of atherosclerotic plaque in apolipoprotein E gene knockout mice（ApoE-/-mice）. Methods：The experimental group of atherosclerotic model was established in ApoE-/- mice fed with a high-fat diet，and the normal C57BL/6 mice fed with normal diet served as the control group. Blood lipid levels were measured and blood samples of aorta were collected at 8 th，12 th，20 th，28 th，and 36 th week after feeding respectively. Oil red O staining and HE staining were used to observe the pathological changes of the aorta，and the quantitative histological and immunohistochemical were analysed meanwhile. Results：The experimental group of low-density lipoprotein（LDL），total cholesterol（TC） levels in each period were higher than the control group（P < 0.05）. With the extension of modeling time，the plaque area and plaque area/lumen area ratio were continually increased in experimental group（plaque area：F=31.473，P < 0.001；plaque area/lumen area：F=178.422，P < 0.001）. The expression quantities of TNX and CD34 increased along with feeding time extendins，and both of them were most expressed at 36 weeks. The TNX and CD34 positive microvessels were highly expressed around the fibrous cap and lipid core，and both were positively correlated（r=0.87，P < 0.001）. However，there were no significant formation of plaques seen in the control group. Conclusion：The expression of Tenascin-X and CD34 increased with the progress of plaque，and the expression sites of Tenascin-X and CD34 in plaque were similar. TNX may be closely related to plaque stability.