Abstract: The fate of nitrogen fertilizer in current crop and succession crops in winter wheat and summer maize rotation system were studied using field 15N micro-plot. The results showed that crop yield would not increase when nitrogen application rate was above N 120kg /hm2. The recovery rate and residual rate of N 120 kg /hm2 were much higher than those of N 360 kg /hm2, but losses rate of N 120 kg /hm2 was much lower than that of N 360 kg /hm2. The residual rate in 0-100cm was 20.9%-48.4% after current crop harvest, the recovery rate of residual nitrogen fertilizer was less than 8%. There still had some residue nitrogen fertilizer after second or third crop harvest; the residual nitrogen fertilizer had much proportion of NO3--N with high application rate. Nitrogen leaching may play an important role in nitrogen losses.