In order to investigate the effect of antioxidants on human blood, vitamin C was selected and added into plastic blood storage bags with CPD, and stored at 25 degrees C. During 6 days of storage, some indexes as ATP, SOD, MDA, K(+) concentration and superoxide radicals were detected and were compared with control group, The results showed that ATP and SOD activity in whole blood with vitamin C during 6 days of storage was higher then that in control group (P < 0.05, P < 0.01), the MDA and plasma K(+) concentrations in stored whole blood with vitamin C during 6 days of storage were lower than that in control group (P < 0.05, P < 0.01), the superoxide radical concentrations in stored whole blood with vitamin C decreased lower than that in control group (30%). The conclusion was made that vitamin C increases activities of ATP and SOD, decreases concentrations of MDA, plasma K(+) and superoxide radicals during blood preservation.