Nitrogen oxides (NOX = NO + NO2) are a major air pollutant under stringent emission regulation in China. The nation has effectively cut its total anthropogenic emission since the peaking around 2012, with cities at the forefront of implementing mitigation measures. However, the city-level emission changes and cross-city contrast remains poorly understood, due to inaccuracies in existing emission data. Using the satellite-based high-resolution PHLET inversion, we derived city-level NOX emissions in China from 2012 to 2020. We found much weaker emission declines in small cities (by 14.7% from 2012–2014 mean to 2018–2020 mean, for the bottom one-third of cities ordered by economic volumes) and medium cities (by 21.3%, for the middle one-third), compared to those in large cities (by 30.6%, for the top one-third) and provincial capital cities in the North Region of China (by 54.2%). Emissions even grew in 43.0% of small cities, compared to 17.4% for large cities. Cross-city emission differences both within each province and among the provinces decreased substantially over time, resulting in a relative shift of emission burdens towards small and medium cities. Such a tendency is hardly resolved by bottom–up emission inventories, highlighting the value of satellite-based high-resolution inversion for tracking city-level emissions to support targeted emission control.

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