The increased nitrogen fertilizer use has greatly boosted the agricultural production in China, however, imposed considerable environmental issues. Reducing nitrogen use in agriculture is inevitable for China to achieve the sustainable development goals. This paper established a partial equilibrium model to evaluate the reducing effects on nitrogen use under scenarios of nitrogen optimized utilization and nitrogen use efficiency improvement among seven crops and seven regions in China. Simulations revealed that: (1) nitrogen optimized utilization helps to reduce 7.73% agricultural nitrogen use in China, soybean turns to be the only exceptional crop that nitrogen use would be doubled; (2) nitrogen use could be continuously decreasing with the nitrogen use efficiency improvement, the reducing rates are 8.28% to 27.91% under 10% to 40% improvement scenarios; (3) among the crops, soybean and peanut have far greater reducing rates than other crops, maize is simulated as the least sensitive crop; (4) East, North and Central China, contribute over 60% of nitrogen use in China, while in Northeast China, nitrogen use performs the least sensitivity to the modelling scenarios. Therefore, this paper suggests that policies and incentives on nitrogen optimized utilization and nitrogen use efficiency improvement are necessary, and heterogeneities in both crops and regions indicate that flexible adjustment strategies of cropping structures in different regions should be taken into consideration towards less agricultural nitrogen use in China.