The effects of nitrogen fertilizer synergist on yield and quality of rice and nitrogen utilization in cold regions were studied in order to provide scientific basis for formulating rational nitrogen management measures and strategies of improving yield, quality and nitrogen use efficiency in paddy field. Field trials were conducted in Fangzheng county, Heilongjiang province in 2017 and 2018 to study the effects of nitrogen fertilizer combined with nitrification inhibitor and urease inhibitor on rice yield, quality, nitrogen utilization and transformation and economic benefits. The results showed that the treatment of N+NI+UI (applying urea combined with nitrification inhibitor CP and urease inhibitor NBPT) significantly increased rice yield, the rice grain, straw and total biomass increased by 6.4%, 4.9% and 5.8% in 2017, 8.8%, 7.2% and 8.2% in 2018, respectively, compared with nitrogen fertilizer treatment (N). Application of nitrogen fertilizer synergist could improve the milling quality, appearance quality and nutritional quality of rice in cold regions, promote the nitrogen absorption of rice and improve the utilization efficiency of nitrogen fertilizer. Compared with N treatment, N+NI+UI treatment increased the apparent nitrogen utilization rate, agronomic efficiency and partial nitrogen productivity of rice by 15.6%, 19.1% and 7.6%, respectively. The combined application of CP and NBPT showed obvious synergistic inhibition effect on nitrogen transformation, delayed and reduced the peak value of NH₄⁺-N content in soil, maintained the NH₄⁺-N content at a higher level at growth stage of rice and extended the nitrogen supply time. Application of nitrogen fertilizer synergist could increase rice in cold area by 2 499.08 yuan/hm². In conclusion, nitrogen fertilizer combined with nitrification inhibitor CP and urease inhibitor NBPT could prolong the nitrogen release cycle, promote nitrogen absorption, improve rice yield and quality, enhance nitrogen use efficiency and increase economic benefits of rice in cold regions.