By exploring the effects of nitrogen reduction combined with nitrification inhibitor DMPP and microbial agents and their combined application on soil nitrogen losses in different ways and nitrogen absorption and utilization of cucumber planting in greenhouse, and to screen the optimum nitrogen losses regulation measures for greenhouse vegetable production system by considering both yield and quality. The cucumber variety "Jinlv 20-10" was used as the experimental material to carry out filed experiment, and six treatments were set up, including no nitrogen application control (CK), conventional nitrogen application (CN), nitrogen reduction application (RN), nitrogen reduction application + DMPP (RND), nitrogen reduction application + microbial agent (RNM), nitrogen reduction application + DMPP + microbial agent (RND+M). Soil nitrous oxide (N₂O) emission, ammonia (NH₃) volatilization and soil profile nitrate nitrogen (NO₃^--N) accumulation, as well as the absorption and utilization, yield, and quality indicators of nitrogen by cucumbers were monitored and analyzed. The results showed that: (1) Compared with CN treatment, the absorption and utilization of nitrogen and nitrogen utilization rate of cucumber were improved by RN, RND, RNM and RND+M treatments. Under the same nitrogen application rate, RND+M treatment could increase total nitrogen absorption in shoots of cucumber by 18.93%, especially the apparent recovery rate of applied nitrogen (REN) and agronomic efficiency of nitrogen fertilizer (AEN) could reached up to 25.30% and 41.16 kg/kg (p<0.05), respectively, showing obvious positive synergistic effect, and better than the application of DMPP or microbial agent alone. (2) The soil N₂O emission, NH₃ volatilization and NO₃^--N accumulation in 0-120 cm soil profile were significantly decreased by 26.38%~41.45%, 28.82%~37.70%, and 13.07%~62.32% in the RN, RND, RNM and RND+M treatments compared with CN, respectively. Under the same nitrogen application rate, RNM treatment had little effect on N₂O emission and NH₃ volatilization in soil, but it could significantly reduce the NO₃^--N accumulation in 90-120 cm soil layer, which was 27.35% lower than that of RN. The N₂O emission in the treatments of RND and RND+M were reduced by 20.11% and 20.47%, and NO₃^--N accumulation in 0—120 cm soil profile were reduced by 30.06% and 24.70%, respectively, reducing the risk of nitrogen accumulation and leaching in the soil but increasing the potential risk of NH₃ volatilization (p>0.05). The performance of prevention and control of nitrogen losses was as follows: RND≈RND+M≥RNM≈RN. (3) Compared with RN treatment, the cucumber yield in RND+M treatments reached up to 70.32 t/hm². Besides, the cost-saving and profit-increasing increased 5150 yuan/hm². Moreover, the effect of RND+M treatment on improving the quality of cucumber fruit was more obvious, and the soluble protein content was 16.36% and 4.01% higher than that of RN and RNM treatment respectively. Comprehensive considering both the economic and environmental benefits, especially from the perspective view of sustainable soil development, under the experimental conditions, nitrogen applied as top dressing at the rate of 316 kg/hm², combined with 2% pure nitrogen of DMPP and 75 L/hm² microbial agent, which is considered to be an appropriate nitrogen losses regulation measure to achieve the high yield and quality, and green and high-quality development of greenhouse cucumber.