In order to compare the glucose regulation effect of different molecular weight chitosan on mice fed high-fat diet, 48 male C57BL/6J mice were randomly assigned to four groups, The control group (Control), which consumed a normal diet, The HF group (HF), which was fed with a high-fat diet, The HF+LWMC and HF+HWMC groups, which were fed with a high-fat diet supplement with 5% low weight molecular chitosan and 5% high weight molecular chitosan, respectively. The diet intake and weight data were collected weekly. The biochemical indicators of serum and liver and the gene expression of PEPCK and G6Pase were determined at the end of the 16 week. The results indicated that supplementation of chitosan could reduce body weights, decrease the levels of serum lipid, and alleviate the liver lipid peroxidation of HF mice. Also, high weight molecular chitosan showed better hypolipidemic effect than low weight molecular chitosan.