Measurements of aerosol particle number concentrations and precipitation intensity during the winter of 2007-2008 were made by WideRange Particle Spectrometer(WPS),disdrometer (OTT Parsivel) and fog monitor (FM_100), in the north suburb of Nanjing. The size distribution characteristics of particles and the relationships between particle size and scavenging coefficients were studied. With a bimodal distribution of diurnal variation, the aerosol particle number concentration, which is much affected by vehicle emission, change of boundary layer height, and the advection of particles, mostly falls between 0.02 and 0.2 μm. Rainfall, snowfall, and fog have different scavenging efficiency on particles. Aitken mode and coarse mode particles are more efficiently scavenged by rainfall and dense fog. Snowfall is efficient in the scavenging of particles smaller than 0.03 m.