To characterize the ambient particles in the Nanjing Jiangbei New Area, a single particle aerosol mass spectrometer (SPAMS) was deployed from December 1 to 31, 2015. A total of 7.478 million particles were analyzed with both positive and negative ion spectra. The air quality of Nanjing during the measurement period was poor, and the percentage of pollution days was 49.2%. The correlation (R) between the SPAMS particle number and PM2.5 concentration was 0.83, showing that the particle number could reflect the trend in the variation of atmospheric pollution. The dominant pollutant source at the monitoring site was coal combustion, followed by vehicle emissions and industrial emissions, with a contribution ratio of 63.5%. The increase in the PM2.5 mass concentration was accompanied by a high proportion of coal combustion or vehicle emissions. A high mixing state between EC, ECOC, and OC and NO2-, NO3-, and SO4- was observed for the sources of biomass burning, dust, vehicle emissions, coal combustion, and industrial emissions.