Abstract: Two cases of sandstorm processes, which occurred in April 1990, were studied. The characteristics of this kind of weather and the reason causing the events are investigated. Through analyzing the samples in collected Yulin, Yan’an, Taiyuan, Hohhot and Beijing, and calculating the sandstorm trajectories, some chemical and physical features are revealed and the source areas are found. In the periods of sandstorm activity the total suspended particulates (TSP) concentrations are higher than normal by several times upto about one order of magnitude. The aerosols of sandstorm consist of mainly the natural lithosphere elements from earth crust, which distribute in large particles (d ＞2.1 μm). The polluted elements from human activity exist in small particles (d＜2.1μm), and their enrichment factors are sharply reduced during the sandstorm.