Abstract: This paper was to investigate the antioxidant activity of different kinds of extracts from Eupolyphaga sinensis Walker (ESW) in vitro. Polypeptides, polysaccharides and water extracts from ESW were prepared by protease hydrolysis and water extracting methods. The scavenging capacity of different kinds of ESW extracts on superoxide anion, hydroxyl and 1,1-Diphenyl-2-2picrylhydrazyl (DPPH·) free radicals were detected by pyrogallol autoxidation, Fe² -phenanthroline method and spectrophotometry methods, respectively. Spectrophotometry was used to assay absorbance values of the hemolysis of red blood cells and liver mitochondrial swelling in the mice. Malondialdehyde (MDA) contents of different tissues from the mice were detected by Thiobarbituricacid (TBA). There was a significant decrease in the scavenging capacity of polypeptides, polysaccharides and water extracts from ESW on superoxide anion, hydroxyl and DPPH free radicals compared with the positive control group, and an increase in the scavenging rate with the extract concentration increasing. As the concentrations of three kinds extracts from ESW were increasing, hemolysis absorption values of red blood cells in experimental groups were more markedly decreased than that in the hemolysis group, while there was a significantly lower hemolysis rate in water extract group compared with polypeptides and polysaccharides groups. MDA inhibition rate of the liver in the polypeptide group was the highest, and that of the kidney in polysaccharide group was higher than in polypeptide and water extract groups. There was an increase in MDA inhibition rate with the increasing of three kinds of ESW extracts. The absorbance value of the liver mitochondria in ESW extract groups was higher than that in the control group with prolong of reaction time. The results showed that polypeptides, polysaccharides and water extracts from ESW had an effective scavenging capacity on three kinds of radicals, an inhibition in hemolysis of red blood cells and hepatic mitochondrial swelling, and a protection of liver and kidney tissues from oxidant injury, which suggested ESW extracts had antioxidant activity in vitro to a certain degree.