Nitrogen deposition has great effects on vegetation characteristics and then affects soil erosion. This study was conducted to quantify the effects of vegetation characteristics induced by nitrogen addition on runoff and sediment yield. The Bothriochloa ischaemum (Linn.) Keng. was planted and applied NH₄NO₃ at levels of 0, 2.5, 5, and 10 g N m^-2 yr^-1 for three years with the bare soil for control. Then all treatments were subjected to simulated rainfall (1.0, 1.5, and 2.0 mm min^-1). Results showed that nitrogen addition increased plant coverage, height, and aboveground biomass of N_2.5, N₅ and N₁₀ treatments, while the root mass density of N₁₀ was the minimum. The grassplots significantly delayed runoff starting time, reduced runoff and sediment yield. With nitrogen addition increasing, runoff starting time delayed and runoff amount decreased, although no significant difference of runoff amount was found under the high rainfall intensity. Moreover, sediment yield would be well estimated by runoff mount, coverage and root mass density with a power function. 5 g N m^-2 yr^-1 seems the optimal nitrogen level in controlling soil loss due to its minimum sediment yield. The different effects of nitrogen addition on grassland community and soil erosion process identified in this study may facilitate the simulation and prediction of soil erosion in semiarid grasslands under future scenarios of global change.