Large amount of nitrogen addition induced much more N2O emission, to explore the soil N2O emissions and its related functional genes adjusting nitrogen metabolism in winter wheat field, a field experiments with nitrogen reduction treatment was carried out in Nanjing, Jiangsu province. There was no significant difference in yield between RN and CN (P>0.05). The experiment was set up three treatments, namely no nitrogen application (N0), traditional nitrogen level (300 kg N/hm2, CN), and 20% nitrogen reduction (240 kg N/hm2, RN). There were two peaks of N2O emission each treatment in winter wheat fields, and the cumulative N2O emission of RN treatment was 31.4% lower than that of CN treatment (P<0.05). At the first peak emission point, the N2O flux was significantly correlated with the copy numbers of AOA and AOB genes in soil (P<0.05), while in the second peak point, the N2O flux was significantly correlated with the copy numbers of nirK, nirS, and nosZ genes in soil (P<0.05). In addition, the direct N2O emission coefficient (FINE) and N2O emissions per unit yield of nitrogen fertilizers in RN treatment were significantly lower than those in CN. It is possible to achieve N2O emission reduction through nitrogen reduction in winter wheat region in Jiangsu Province, and the process of emission reduction is mainly controlled by N-functional genes. This study revealed the important role of nitrogen fertilizer management in reducing emissions in agricultural ecosystems, and provided evidences for proposing reasonable nitrogen reduction strategies.