In order to study the characteristics of air pollution in winter in Nanjing, one-month intensive observations were conducted from November 24 to December 23, 2016. Based on the observation data of Caochangmen station, Gulou station and Xianlin station in Nanjing, the temporal and spatial variation characteristics of major air pollutants in urban and suburban areas and their correlations with meteorological elements were analyzed. The study found that the monthly average mass concentrations of PM_2.5, PM₁₀, NO₂, O₃, CO and SO₂ in Nanjing during the observation period were 52.84—84.34 μg·m^-3, 88.36—120.34 μg·m^-3, 49.98—51.66 μg·m^-3, 24.85—50.57 μg·m^-3, 0.99—1.2 mg·m^-3 and 22.1—26.48 μg·m^-3, respectively. In the near ground, the mass concentrations of urban air pollutants were higher than those of the suburbs, of which urban O₃ was 61.0% higher than that of the suburbs. In urban areas, except for NO₂ and CO, the mass concentrations of atmospheric pollutants of Gulou station were higher than those of Caochangmen station. The mass concentration of PM_2.5 of Gulou station was 42.7% higher than that of Caochangmen station. The maximum hourly mass concentration of PM_2.5 was 210.93 μg·m^-3, and when the heavy haze occurred, usually the wind speed was lower and the temperature was higher; when the mass concentrations of PM₁₀, PM_2.5 and NO₂ in the suburbs were higher, the most frequent wind direction was south; when the mass concentrations of O₃ and SO₂ were higher, the most frequent wind direction was west and southwest, respectively. By using HYSPLIT model, it was found that the polluted air masses on December 4—8 and 16—20 came from the western region and the northern region respectively, and using cluster analysis it was found that 45% of the polluted air masses affecting Nanjing in December came from the western region and moved faster, meanwhile, 55% came from the northern region and moved slower. It could be seen that the formation of air pollution occurred in winter in Nanjing was not only related to local emissions, but also related to local meteorological conditions. The influence of long-distance transportation in western and northern regions couldn't be ignored.