Abstract: Chemical and environmental significance of insoluble particles in precipitation are studied using methods of parameter comparison and correlation analysis at alpine and rural sites on the Urumqi river valley in Tianshan Mountains.The HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory)model is also employed to examine the transport process of air mass and insoluble particles in this region.Results show that the concentration,the size distribution and the chemical constitutes of dust particles in precipitation all exhibit significant seasonality at both sites.The dust concentration increases in winter and spring seasons and decreases during summer and autumn periods,showing a negative correlation with seasonal changes in precipitation.This indicates the significant influence of Asian dust storm in the river valley.The volume-size distribution reveals that large-sized particles are found in winter and spring seasons,while,small-sized one appears to be in summers and autumns.The seasonal variation in chemical constitutes of dust particles indicates that both regional atmospheric environment and human activities of Central Asia may have influence on the formation of regional precipitation.