The Chinese government has already been aware of NO_x emissions because they are mainly responsible for a complex air pollution situation in China. The main aim of this research is to disclose the temporal variations and the spatial patterns of NO_x emissions of Chinese provinces, and then analyze reduction potentials. The main findings are as follows. (1) From 2006, the total NO_x emissions in China continued to increase and then reached the summit in 2011, and began to decline until 2017. The two largest sources of NO_x emission in China are industry and vehicle. (2) Most provinces with high NO_x emissions are mainly concentrated on the North China Plain, but they have substantially reduced NO_x emissions recently. However, from 2011 the share of NO_x emissions from vehicles of all provinces sharply increased because of the ever-growing private vehicle consumption, indicating that the problem of vehicle emissions had become increasingly prominent. (3) Per capita NO_x emissions presented an inverted U-shaped curve, similar to the total NO_x emissions. From the coefficients of variation and the kernel density estimates, we conclude that the differences in cross-province per capita NO_x emissions narrowed notably after 2015. In other words, provinces with higher per capita NO_x emissions have greater reduction potentials, and will catch up with provinces with lower per capita NO_x emissions.