Objective： To study the regulative function and mechanism of konjac glucomannan oligosaccharides （KOS） on hyperlipidemia and liver injury in obesity model rats. Methods： A rat model of nutritional obesity was established by high fat diet induction. The rats were divided into three groups： normal control group （NC）， high fat model group （MC） and konjac glucomannan oligosaccharides administration group （KOS） after the model established. They were fed basic diet， high fat diet and intervention diet respectively. After administration for 6 consecutive weeks， the changes of body weight， lipid metabolism， oxidative stress and liver function indexs in obese rats were investigated and compared. Results： After 8 weeks feeding of high-fat diet， the obesity model was considered to be built when the weight of the rats fed with a high fat diet exceeded 20% of the average weight of rats fed with a basic diet. Compared with the MC， the levels of TG， TC， LDL-C， MDA， ALT （P<0.01） and AST （P<0.05） were significantly decreased. In contrast， the levels of serum SOD and GSH-Px were significantly increased（P<0.01）. Meanwhile， the liver weight and index was reduced. Liver histology showed the decrease of liver injury. Besides， with the model control group， the body weight of obese rats reduced after the administration of KOS. The levels of serum the levels of AKP had an decreasing tendency， and the level of HDL-C had an increasing tendency. Conclusions： KOS administration can lighten the weight of obese rats， ameliorate the lipid metabolism disorder effectively， improve the ability of oxidative stress， alleviate the symptoms of hyperlipidemia， and resist the liver injury caused by obesity.