Objective To investigate the effect of oxidative stress on diabetic erectile dysfunction( ED). Methods Diabetes mellitus(DM) was induced by streptozotocin (STZ) injection. Eight weeks and twelve weeks later, penis erectile function was detected by injecting apomorphine. The concentrations of malondialdehyde ( MDA) and total anti-oxygen capability (T-AOC) in penis were measured. Western blotting was used to measure nuclear factor E2related factor 2（Nrf2） in both control and diabetic rat penis tissues in present study. Results Compared with control group, the erection times of DM rats decreased significantly. The mean level of MDA in penis of DM rats were higher than that of control group（EM>P/EM>﹤0.01）, and the mean level of T-OC in DM rats was lower than that of control（EM>P/EM>﹤0.05）. Nrf2 protein expression decr