Abstract: To investigate the effect of different molecule weight (150ku and 850ku) and doses of oat β-glucan on plasma lipid levels and free fatty acids of mice with high cholesterol mice. The high cholesterol mice were induced by high-fat and high sugarforage. Fasting blood plasma total cholesterol (TC) , triglycerides (TG) , high-density lipoprotein cholesterol (HDL-C) , low density lipoprotein cholesterol (LDL-C) and free fatty acid (FFA) were determined after treatment 4, 7, 10-weeks. Results showed that different doses and molecular weight of β-glucan could significantly reduce the fasting plasma TC and LDL-C level, it also could make the TG level back to normal, but it was no effect on HDL-C. The low molecule weight (150ku) of β-glucan could significantly improve the plasma FFA level. It suggested that different molecule weight of β-glucan had different effects on plasma lipid and FFA, and the effect relied on the time and the dose of β-glucan.