In 19 and 20 March 2010, the annual strongest dust event occurred over East Asia, for the reports from National Meteorological Center of CMA (China Meteorological Administration) showed that 16 provinces (cities) of China were affected by the dust storm, and the air pollution index (API) given by Ministry of Environment Protection of China exceeded 300 in 13 Chinese cities. An air quality modeling system RAMS-CMAQ was employed to simulate the spatial and temporal features of this dust event, and analyze its impacts on air quality and regional radiative effect in East Asia. The modeled mass concentrations and aerosol optical depth (AOD) of dust and other aerosol species are generally in good agreement with surface observations and satellite measurements. Numerical analysis shows that the dust storm generated over Mongolia and west of Inner Mongolia, and swept central, eastern and southern China, also including the East China Sea. The highest value of dust concentration exceeded 3000 μg/m3 in the source area and waved from 200 to 1000 μg/m3 in the downstream areas. The high AOD values mainly contributed by dust ranged from 0.5 to 1.5, which means the regional visibility and radiation would be significantly impacted by the dust particles. The direct radiative forcing of dust was also obviously strong with values from –5 to –30 W/m2 appeared over the regions where dust storm swept. This value is almost equal to the radiative effect of total aerosol components over these areas.