A severe dust storm over northern China in April of 2009 (i.e., 22-24 April) is studied. Firstly, the relationship between the meteorological variables at surface, PM10 and the intensity of dust storm on April 22, 2009 is analyzed. The results show that Mongolian cyclone and its cold front are the main system producing the strong dust storm. The temperature, surface pressure, wind and PM10 are closely related to the intensity of the dust storm. Secondly, an integrated dust storm modeling system is employed to simulate this process. The simulation results show that the modeling system is capable for better describing the main characteristics of dust storm. And the scope of simulated dust concentration value is consistent with the strong dust storm. Comparing with the morning and afternoon dust concentration distribution, we find it has daily change. The dust emission areas with vertical sand flux over 50 mg·m-2·s-1 are Tarim Basin， Gansu Province， western Inner Mongolia and southern Mongolia. The vertical transportation of dust concentration is below 550 hPa, and the horizontal transportation of dust is driven by strong wind in middlelowerlevel troposphere. The particle size which contributes significantly to the dust emission is different due to the variety of land, however, the quantities of particles with diameter from 2 μm<d≤11 μm are predominated. The scope of simulated dust concentration value is consistent with the strong dust storm.