Abstract: Indigowoad Root was extracted with 95% ethanol, and then the extract was partitioned with petroleum ether, chloroform and n-butanol successively. The crude polysaccharides was obtained from water extract and ethanol precipitate. The antioxidation of different end extracts were studied by potassium ferricyanide reduction assay, superoxide anion free radical scavenging assay and 1, 1-diphenyl-2-picrylhydrazy1 (DPPH) radical scavenging assay. The relationship between the antioxidant activity and the content of total sugar was analysed. The results showed that the antioxidant activities had great difference in six polar extracts from Indigowoad Root, and the content of total sugar had low correlation with the activities. The chloroform extract showed that the highest radical scavenging rate on superoxide anion free radical and DPPH free radical, and the IC50were 3.38mg/mL and 0.19mg/mL, respectively. The chloroform extract was identified as an important fraction for further screening antioxidant components except polysaccharides. The highest content of total sugar came from crude polysaccharides extract and the content was 18.66%. The antioxidation could be one of the mechanisms in detoxication of Indigowoad Root.