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The three-dimensional evolution of an East Asian dust storm during 23-26 April 2009 was investigated by utilizing a regional air quality model system (RAQMS) and satellite measurements. This severe dust storm hit Mt. Tai in east China with daily mean PM 10 concentration reaching 1400 mu g/m(3) and the model captured the PM10 variation reasonably well. Modeled spatial distributions of AOD and vertical profiles of aerosol extinction coefficient during the dust storm were compared with MODIS and CALIPSO data, demonstrating that RAQMS was able to reproduce the 3D structure and the evolution of the dust storm reasonably well. During early days of the dust storm, daily mean dust-induced AOD exceeded 2.0 over dust source regions (the Gobi desert and the Taklamakan desert) and was in a range of 1.2-1.8 over the North China Plain, accounting for about 98% and up to 90% of total AOD over corresponding areas, respectively. The top of the dust storm reached about 8 km over east China, with high dust concentration locating at around 40 degrees N. Dust aerosol below 2 km was transported southeastward off the Gobi desert while dust above 2 km was transported out of China along 40 degrees-45 degrees N.