Abstract: To study the mechanism of dietary fiber(DF) on antioxidation in rats,we compared the effect of three kinds of dietary fiber reducing the level of lipid peroxidation with food resdtriction.Wistar rars(50)were randomely divided into 5 groups,3groups were fed with the fibers at a level of 10% in weight,the 4th group were restricted food at level 10% in weight,the 5th consumed stock food as control.After 3 months feeding,for the three dietary fiber groups,the lipid amounts in stool were significantly increased,MDA in serum and RBC membrane were significantly lower than that of the control group.But for the restriction food group,there were no significantly differences to the control group.These results may suggest that the main reason why dietary fiber could prevent oxidation is that DF can affect lipid metabolism.