Themesoscale numericalmodel MM5(V3)was used to simulate a strong duststorm process occurred in the northern and central Inner Mongolia during the period from 20:00BST March 26 to(20:00BST)March 28,2004.Themodel outputs were used for detailed diagnostic studies of dry air intrusion.Diagnostic results show that dry air intrusion plays an important role in the development of the duststorm process.Dry air intrusion brings high potential vorticity from the upper level of troposphere to the low level,promoting the development of the cyclone and convective activities at the low level of troposphere,and then the genesis of the strong duststorm.