<p>As a major alkaline gas in the atmosphere, NH<sub>3</sub> significantly impacts atmospheric chemistry, ecological environment, and biodiversity. Gridded NH<sub>3</sub> emission inventories can significantly affect the accuracy of model concentrations and play a crucial role in the refinement of mitigation strategies. However, several uncertainties are still associated with existing NH<sub>3</sub> emission inventories in China. Therefore, in this study, we focused on improving fertilizer application-related NH<sub>3</sub> emission inventories. We comprehensively evaluated the dates and times of fertilizer application to the major crops that are cultivated in China, improved the spatial allocation methods for NH<sub>3</sub> emissions from croplands with different rice types, and established a gridded NH<sub>3</sub> emission inventory for mainland China with a resolution of 5 min × 5 min in 2016. The results showed that the atmospheric NH<sub>3</sub> emissions in mainland China amounted to 12.11 Tg, with livestock waste (44.8 %) and fertilizer application (38.6 %) being the two main NH<sub>3</sub> emission sources in China. Obvious spatial differences in NH<sub>3</sub> emissions were also observed, and high emissions were predominantly concentrated in North China. Further, NH<sub>3</sub> emissions tended to be high in summer and low in winter, and the ratio for the July–January period was 3.08. Furthermore, maize and rice fertilization in summer was primarily responsible for the increase in NH<sub>3</sub> emissions in China, and the evaluation of the spatial and temporal accuracy of the NH<sub>3</sub> emission inventory established in this study using the WRF-Chem and ground station- and satellite-based observations showed that it was more accurate than other inventories.</p>