Objective:To investigate the inhibitory effects of different doses of Astragalus membranceus on the oxidative stress in the kidneys of diabetic rats  Methods:Totally 40 healthy male Wistar rats were used, from which 8 rats were randomly selected as normal control group. Then the rest rats were induced to diabetic rat models by injections of streptozotocin, and the successful models were divided randomly into four groups:the diabetes mellitus group, the low dosage Astragalus membranceus (A,l,) group, the middle dosage Astragalus membranceus (A,m,) group and the high dosage Astragalus membranceus (A,h,) group. After 12 weeks of intervention, the biochemical test was used to measure the levels of 24-hour urine protein quantitate, renal function, and other tests were done to measure the activity of superoxide dismutase (SOD), the content of malondialdehyde (MDA) and 8-hydroxy-deoxyguanosine (8-OHdG) in the renal cortex  Results:The content of MDA and 8-OHdG in the Astragalus membranceus treatment groups were markedly lower and SOD activity significantly increased than those in the diabetes mellitus group (P,<,0.05, P,<,0.01), and renal function improved significantly (P,<,0.01), and pathological changes obviously alleviated; the Astragalus membranceus treatment high dose group improved most obviously than other groups  Conclusion:The traditional Chinese herbal medicine Astragalus membranceus could inhibit the oxidative stress in the kidneys of diabetic rats with an obvious dose-effect relationship.