Abstract: Many researches on sulfate aerosols have been done in the last two decades, which contributed significantly to our understanding of the emission, concentration, optical properties and radiative forcing of sulfate in the atmosphere. However, not much attention was paid to the studies on nitrate at the beginning since the concentration of nitrate aerosol in the atmosphere was much less than that of sulfate aerosol. Recent studies show that the scattering properties of nitrate are even stronger than that of sulfate in some wave bands. Besides, the proportion of nitrate in total anthropogenic aerosols shows an increasing trend since the emissions of sulfate aerosol have been greatly reduced due to the controlling to its precursors at present, while the emissions of nitrate aerosol increase rapidly, leading to higher radiative forcing caused by nitrate than by sulfate. It is very likely that nitrate aerosol will become an important radiative forcing factor that will affect climate change at regional and seasonal scales in the future, especially over China due to the increasing large emission. Therefore, the present paper reviews the researches on nitrate aerosols from the perspectives of emission, concentration change, distribution of optical depth, and radiative forcing. Finally, the direction of research on nitrate aerosols in the future is discussed.