Abstract: The trajectories of air parcels throu;h the ten big cities of China (Beijing, Xian and so on) have been computed using the data of wind fields on 1500m elevation. Based on these trajectories and the end points of trajectories, it is estimated that the impact due to Long-rang transport of pollutants from the city sources and these cities would be influenced by the surrounding distant sources in different seasons. An advantage of the statistical trajectory model is expected that the error of the individual trajectories tends to be averaged out in the long run.