The different straw application ways(returning to the field or leaving off the field)and the varying nitrogen input levels could result in significant spatial variations in N2O emissions from calcareous loam soil. To determine the extent of this variation’s impact on N2O emissions，an indoor cultivation experiment was conducted with two methods:the S group(1% dry soil mass of straw added，simulating straw returning to the field)and the NS group(simulating straw leaving the field)，along with five nitrogen gradients of N 0，100，200，300，and 500 mg·kg-1，totaling 10 treatments. The results showed that under N 0 mg·kg-1 addition，the N2O emissions of the NS group were significantly higher than those of the S group.Under N 100 mg·kg-1 addition，there was no significant difference in N2O emissions between the NS group and the S group.However，when the nitrogen input exceeded N 100 mg kg-1，the N2O emissions of the S group were significantly higher than those of the NS group. Among them，the N2O emissions of the S group at N 200，300，and 500 mg·kg-1 additions were 1.39，1.47，and 2.35 times those of the NS group，respectively. It was also found that the mineral nitrogen(Nmin，including NH4+-N，NO^3--N，and NO₂--N)of the NS group and the S group significantly increased with the increase in nitrogen addition. The N2O emissions of the S group and the NS group were significantly positively correlated with the NO₂--N concentration，but had a weaker correlation with NH4+-N and NO^3--N. The fitting curve showed that the N2O emissions of the S group increased exponentially with the increase in nitrogen quantity，while those of the NS group showed a basically linear growth trend. Additionally，the N2O emission coefficient of the S group decreased gradually with the increase in nitrogen input，while that of the NS group increased with the increase in nitrogen input. The main reason for this was that the addition of straw coupled with high nitrogen levels increased the soil carbon-nitrogen ratio，stimulating the abundance of key functional microorganisms and thereby inducing the production of N2O gas. Based on these conclusions，this study suggested that there was a highly significant difference in the impact of whether or not straw was added on N2O emissions under different nitrogen gradients. In the future，when predicting N2O emissions in agricultural systems，the influence of whether or not straw is returned to the field coupled with different nitrogen inputs should be fully considered. Considering the singularity of the environmental factors in the cultivation test，further field tests are still needed to determine the emission coefficient.