To investigate the antioxidant activity of Taibai Qiyao Panacis Majoris Rhizoma in vitro.Methods:The antioxidant activities of Panacis Majoris Rhizoma aqueous extracts，sapanins and polysaccharides were investigated by evaluating their ability to reduce iron，scavenge diphenyl-2-trinitrophenylhydrazine(DPPH) free radical and superoxide anion(·O2-) free radical，and protect against bovine serum albumin(BSA) damaged by Cu2+/H2O2 and RAW264.7 of mouse macrophages damaged by H2O2.Results:Different concentrations of Panacis Majoris Rhizoma aqueous extracts，saponins and polysaccharides all had certain ability to reduce iron and to scavenge DPPH free radical and ·O2- free radical in a concentration-dependent manner of which Panacis Majoris Rhizoma saponins had the strongest ability to reduce iron and scavenge free radicals; different concentrations of Panacis Majoris Rhizoma aqueous extracts，saponins and polysaccharides had protective effects on protein oxidative damage induced by Cu2+/H2O2，of which Panacis Majoris Rhizoma aqueous extracts had the strongest protective ability; different concentrations(6.25～100 μg/mL) of Panacis Majoris Rhizoma aqueous extracts，saponins and polysaccharides had protective effects on RAW264.7 cells injured by H2O2 in a concentration-dependent manner，of which Panacis Majoris Rhizoma saponins at the concentration of 100 μg/mL had the strongest protective effect.Conclusion:Panacis Majoris Rhizoma aqueous extracts，saponins and polysaccharides all have certain antioxidant capacity in vitro，but there are some differences in their antioxidant capacity at different levels.