Abstract: Soybean is one of the most sensitive to water in legume crops. Clearing the effect of drought stress on leaf physiological characteristics of soybean is an important theoretical and practical significance for better managing water .This test measured the leaf SOD activity and MDA content at different growth stages under the condition of drought stress and consequent re-watering, choosing the drought-resistant variety(Heinong 44) and the sensitive variety(Heinong 65) as materials. The results suggested that SOD activity initially increased and then decreased with increasing water stress , further the rate of increase was that the flowering stage >the seedling stage >the filling stage .SOD activity of Heionng 44 is significantly stronger than Heinong 65 . Increasing drought stress MDA content initially increased. The rate of increase was that the seedling stage >the flowering stage >the filling stage and the MDA content of Heinong 44 obviously lower than Heinong 65. After re-watering,SOD activity and MDA content of both cultivars gradually decreased approaching the control treatment. Whereas re-watering at seeding stage was better for MDA content to recover than at flowering stage.MDA content can’t recover when re-watering at filling stage.