Object: There is growing concern about the role of monocytes-macrophages in the progress of atherosclerosis (AS). However, the mechanism of lipid change in those cells in the foaming process is not clear. Methods: LDL was isolated by density gradient centrifugation at one time and was made as Ox-LDL. Furthermore, the changes of lipid composition and cellular shape could be dynamically observed in rat macrophages. Results: the purity level of purified LDL can reach 92.39%. The increased red lipid droplets in macrophages were observed by the experimental method of cellular morphology. The electron microscopy showed that chromatin around nucleus , numerous mitochondria and ribosome in the sparse cytoplasm. In LDL group, with the increasing of LDL level , the TC, FC, CE were all increased .There was the same result in Ox-LDL group. Conclusion: Interaction of Ox-LDL and monocytes-macrophages could promote part of arterial wall to form the cells of AS feature. OX-LDL was easier to make monocytes/macrophages change to foam cells than LDL. Moreover, it was confirmed that high level of OX-LDL can lead to damage of cells membrane