To examine the effect of Codium fragile on blood cholesterol and lipid metabolism, hyperlipidemia was induced in experimental animal rats through the administration of a hypercholesterolemic diet. Codium fragile powder was then administered to the rats for 5 weeks, after which, blood biochemical changes such as blood cholesterol, Aspartate Aminotransferase (AST: serum SGOT) and Alanine Aminotransferase (ALT: serum SGPT) enzyme activity, etc. were determined. And histological changes in liver cells were examined using an electron microscope. Codium fragile treatment resulted in a significant reduction of the levels of total cholesterol, blood triglyceride and low-density cholesterol (LDL. Chol) compared to the control rats. In contrast the expression levels of high-density cholesterol (HDL. chol.) were increased. The AST value of the Codium fragile administration group was significantly reduced and the blood ALT value of the Codium fragile group showed a significant decrease in comparison to the negative control group. In summary, this study demonstrated the beneficial possibilities of Codium fragile in improving the abnormality of lipid metabolism caused by liver cell damage and hyperlipidemia.