Nitrogen is the key nutrient for crop growth, and proper N applications not only improve soil productivity but also reduce N losses. Knowledge of soil N supply is the basis for making optimum N fertilization recommendation. Field experiments were conducted to explore effects of different N strategies, including N application rates and topdressing, on nitrogen use efficiency (NUE) and spatial-temporal distribution of NO₃^--N. Results show that NUE obviously decreased with increasing N rate. Soil NO₃^--N content was highest at the beginning of winter, and then decreased, but it increased with nitrogen application rate and more significant in the deep soil layer (40~60 cm) than in the middle soil layer (20~40 cm). After crops were harvested, N deficit was found in zero N treatment appeared N deficit, while N surplus was in all fertilization treatments, and increased with N application rate. This study recommends that it is not advisable to apply a large quantity of N fertilizer all at once as basal dressing. Splitting N application favors N absorption by wheat and reduces soil nitrate accumulation in the deep soil layer.