Using the static chamber-gas chromatograph method, a field experiment was conducted to investigate the effects of no any fertilizers (CK), single application of manure (M), conventional fertilization (CON), optimum fertilization by reduction of chemical fertilizers (OPT), and basis of OPT + regulation soil C/N ratio by addition of crop residues (OPT + C/N) on soil N₂O emission flux, ratios and amounts of N₂O emission during spring cucumber season and summer fallow in the Yellow River irrigation region of Ningxia. The results indicated that peaks of soil N₂O emission flux under different fertilization were generally happened in the first or third days after drip fertigation in the cucumber season and flood irrigation in the summer fallow. After base fertilization, topdressing of spring cucumber and during summer fallow, soil N₂O emission flux in treatments OPT and OPT + C/N were decreased by 3.6% – 47.2%, 5.9% – 49.9%, and 14.7% – 46.6% compared to treatment CON, respectively. Accumulation amounts of N₂O emission under different fertilization in spring cucumber season and summer fallow were ranged from 2.05 ~ 9.98 and 3.55 ~ 7.23 kg/hm², respectively; compared to treatment CON, those in treatments OPT and OPT + C/N were decreased by 26.2% – 34.3% and 29.6% – 33.7%, respectively. Ratios of N₂O emission from application fertilizers in spring cucumber were ranged within 0.43% – 0.71%, and the total ratios of N₂O emission were ranged within 0.54% - 1.04% during spring cucumber-summer fallow. Significant linear positive correlation was found between N application rate and total amount of N₂O emission (R² = 0.778); Soil N₂O emission fluxes under different fertilization treatments were significantly or extremely significantly positively correlated with 5 cm of topsoil temperature (R² = 0.47 – 0.68), and extremely significantly positively correlated with 0 – 20 cm of soil moisture (R²= 0.63 – 0.88). Therefore, compared to the conventional application of N fertilizer by the local farmers, both reducing synthetic N fertilizer by 50% or reducing N fertilizer combined with adding 7.5 t/hm² wheat residues to regulate soil C/N ratio could obtain the goal of reducing N₂O emission in the greenhouse field.