Abstract: Taking ‘Huayu 22’ peanut as test material, effect of soil water content and nitrogen fertilization on the leaf physiological activities and root morphological characteristics of peanut plants were analyzed. Two levels of soil water condition were: (1) wellwatered condition and (2) moderate water stress, and three levels of nitrogen were: (1) none nitrogen (N₀), (2) moderate nitrogen (N₁, 90 kg·hm^-2) and (3) high nitrogen (N₂, 180 kg·hm^-2). The results showed that N₁ significantly increased the peanut yield under two water conditions, but showed no significant effect on harvest index compared with N₀. Under water stress condition, N₁ had no significant effects on total root biomass and total root length, but the total root surface area was remarkably increased. The nitrogen fertilization significantly increased the root length and root surface area in 20-40 cm soil layer, and N₂ significantly increased the root biomass and root surface area in the soil layer below 40 cm. The application of nitrogen remarkably increased CAT and POD activities in leaf, while MDA content was decreased with the increase of nitrogen level. Under wellwatered condition, the root biomass, root length and root surface area in the soil layer below 40 cm and total root surface area were significantly reduced by nitrogen application, however, only N₁ could increase leaf protective enzyme activities. Correlation analysis showed that the root length in 20-40 cm soil layer and SOD, CAT, POD activities in leaf were highly significantly related with peanut yield.