OBJECTIVE：To compare the difference in the antioxid ant effect of fresh Rehmannia glutinosa ，dried R. glutinosa ， R. glutinosa preparata during ancient characteristic processing and its polysaccharides before and after processing on aging model rats，and to provide reference for the processing of R. glutinosa . METHODS ：The sample of R. glutinosa preparata was prepared according to ancient characteristic method. During the processing ，the fresh and dried R. glutinosa samples were retained. Then crude polysaccharide were extracted from fresh R. glutinosa and Rehmanniae radix preparata by water extraction and alcohol precipitation. Totally 96 rats were divided into blank group （water），model group （water），positive control group [vitamine C ，100 mg/（kg·d）]，fresh R. glutinosa group [ 700 mg/（kg·d）]，dried R. glutinosa group [ 135 mg/（kg·d）] ，Rehmanniae radix preparata group [ 135 mg/（kg·d）]，fresh R. glutinosa polysaccharide group [ 1 400 mg/（kg·d），by the weight of fresh R. glutinosa ] and Rehmanniae radix preparata polysaccharide group mg/（kg·d），by the weight of Rehmanniae radix preparata] ， with 12 rats in each group. Except for blank group ，other 制。E-mail：zhouyan1221@163.com groups were given D-galactose [ 125 mg/（kg·d）] on neck and back to induce sub-acute aging model. At the same time ，they were given relevant medicine in tragastrically，once a day ，for consecutive 56 days. After last admin istration，the liver ，brain，kidney，spleen，heart and thymus indexes were determined. The total antioxidant capacity （T-AOC），superoxide dismutase （SOD）activity，catalase（CAT）activity and MDA content in serum ， liver，brain and kidney were determined. RESULTS ：Compared with blank group ，organ indexes of rats in the model group were decreased significantly （P＜0.05 or P＜0.01）；T-AOC，SOD activity and CAT activity in serum ，brain，liver and kidney tissue were decreased significantly （P＜0.01），while MDA content increased significantly （P＜0.01）. Compared with model group ，the organ indexes of brain ，liver and kidney ，SOD activity in serum and kidney of fresh R. glutinosa group were not significantly increased （P＞0.05）；kidney index ，T-AOC in serum and brain ，SOD activity in serum ，liver and kidney tissue were not significantly increased in the dried R. glutinosa group（P＞0.05）；kidney index ，T-AOC in serum and cerebral tissue ，SOD activity in serum were not significantly increased in fresh R. glutinosa group（P＞0.05）；other organ indexes ，T-AOC，SOD activity and CAT activity in serum and tissues were increased significantly in other groups （P＜0.05 or P＜0.01），while MDA content in serum and tissues were decreased significantly in all administration groups （P＜0.05 or P＜0.01）. Compared with fresh R. glutinosa group，T-AOC in serum was decreased significantly in dried R. glutinosa group（P＜0.01），and there was no significant difference in other indexes （P＞0.05）；kidney and spleen indexes of rats in Rehmanniae radix preparata group were increased significantly （P＜0.05），T-AOC in renal tissue ，SOD activity in serum ，cerebral tissue and renal tissue ，CAT activity in cerebral and liver tissue were increased significantly （P＜0.05 or P＜0.01），while MDA in cerebral and liver tissue were significantly decreased （P＜ 0.01）. CAT in cerebral tissue and liver tissue of rats in Rehmanniae radix preparata group were significantly higher than those in positive control group （P＜0.01）. Compared with fresh R. glutinosa polysaccharide group ，spleen and renal indexes of rats in Rehmanniae radix preparata group were increased significantly （P＜0.05 or P＜0.01），T-AOC，SOD activity and CAT activity in serum and cerebral ，liver，renal tissues were increased significantly （P＜0.05 or P＜0.01）. T-AOC and CAT activity of cerebral ， liver and renal tissues in Rehmanniae radix preparata group were all significantly higher than those in positive control group （P＜ 0.05 or P＜0.01）. CONCLUSIONS ：In the aspect of increasing organ index and improving the activity of antioxidant enzymes in serum，cerebral，liver and