Three-year particle number size distributions were analyzed to characterize the size distributions and optical properties of the particles in the urban atmosphere of Beijing, China during dust events in the springs of 2004–2006 in combination with AERONET sun/sky radiometer data. The dust events were categorized as two different types (type 1 and 2). This categorization of the dust events was confirmed by the aerosol index images, columnar aerosol optical properties, and vertical potential temperature profiles. Dust particles dominated the total particle volume concentration (3–10000 nm) (over 70%) for the dust events in type 1, which happened under strong wind speeds. In this type, relatively purer dust particles were observed in the urban atmosphere. The events in type 2 with a longer stagnation time in the urban area and lower ratio of coarse mode particle to the total particle volume concentration occurred under stable local weather conditions. During the events in type 2, a superposition of the dust particles and anthropogenic aerosols was observed. The comparison of columnar optical properties among type 1, 2, and heavy pollution periods shows that the superposition of dust particles and anthropogenic aerosols can result in much higher AOD than pure dust particles in the urban atmosphere of Beijing. By comparing the particle volume size distributions retrieved from AERONET with those obtained from the Twin Differential Mobility Particle Sizer measurements, a discrepancy between the ground-based and column integrated particle volume size distributions was found, especially obvious for the coarse mode particles.