Aims Nitrous oxide (N_2O) is one of the most important greenhouse gases, which contributes a lot to global warming. However, considerable variations are observed in the responses of soil N_2O emissions to experimental warming, and the underlying microbial processes remain unknown. Methods A warming experiment based on open-top chambers (OTCs) was set up in a typical alpine steppe on the Qinghai-Xizang Plateau. The static chamber combined gas chromatography method was applied to investigate soil N_2O flux under control and warming treatments during the growing seasons in 2014 and 2015. Gene abundances of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) were quantified using quantitative real-time PCR. Important findings Our results showed that the warming treatments increased soil temperature by 1.7 and 1.6 °C and decreased volumetric water content by 2.5% and 3.3% respectively during the growing season (May to October) in 2014 and 2015. However, there were no significant differences in other soil properties. Our results also revealed that, the magnitude of soil N_2O emissions exhibited substantial variations between the two experimental years, which were 3.23 and 1.47 mug·m~(-2)·h~(-1) in 2014 and 2015, respectively, but no significant difference in N_2O fluxes was observed between control and warming treatments. AOA and AOB abundances are 15.2 * 10~7 and 10.0 * 10~5 copies·g~(-1) in 2014, and 5.0 * 10~7 and 4.7 * 10~5 copies·g~(-1) in 2015, with no significant differences between control and warming treatments during the experimental period. Furthermore, warming-induced changes in N_2O emissions had no significant relationship with the changes in soil temperature, but showed a significant positive correlation with the changes in soil moisture at seasonal scale. Overall, these results demonstrate that soil moisture regulates the responses of N_2O emissions to experimental warming, highlighting the necessity to consider the warming-induced drying effect when estimating the magnitude of N_2O emissions under future climate warming.