The purpose rests on studying functions of corn active polysaccharide in reducing weight and fat. The selected 80 mice (half male, half female) were randomly divided into 5 groups: control group, adiposity model group, and corn active polysaccharide 3.50, or 1.75, or 0.88g/kg dose group. Each group except the control group was dosed once a day for 35 days and was weighed once every 7 days. Another 80 mice (half male, half female) were grouped,fed and weighed in the same way as the above 24 hours after the last dosage, the mice were killed, abdominal fat was weighed and the fat index number was calculated. Another 80 mice (half male, half female) were grouped, fed and weighed in the same way as the above 24 hours after the last exhibition, their eyeballs were removed and the blood was extracted. Its biochemical indexes were determined by HITACHI7080 auto analyzer. The results of test showed that: the corn active polysaccharide can obviously all reduce the adiposity mices’ weight, fat index number, TC, TG, LDL and GLU, yet improve their HDL in blood serum, so the corn active polysaccharide possesses great functions in reducing weight and fat.