Abstract: A nutrient solution experiment was conducted to investigate the effect of different levels of nitrogen supply on growth and root water uptake characteristics of soybean seedlings. The results showed that at the same growth period, both the root dry weight and shoot dry weight were highest when nitrogen concentration was 2 mmol·L^-1. Nitrogen concentration had less effect on root dry weight than on shoot dry weight. Within 30 DAS (DAS:days after sowing), daily average root-water-uptake rates per plant were insignificant among different nitrogen supply levels. After 30 DAS, daily average root-water-uptake rates per plant increased gradually with increasing nitrogen level but changed slightly when nitrogen concentration was over 2 mmol·L^-1. Under optimal water condition, potential root-water-uptake per unit root length was not a constant, which was affected by nitrogen supply levels and growth periods.