Abstract:Through synoptical diagnosis and numerical study of the Sichuan torrential rain events,one in the western part on July 11~14,1981 and the other in the eastern on July 26~ 29,1982,we come to the conclusion that the western event was largely related to the enhanced Tibetan vortex which migrated east to meet SW flow along the brim of a subtropical high,resulting quite easily in the event whilst the eastern event occurred due to the fact that the Plateau lowvalue system moved rather fast and the eastern Tibet was under the effect of NW flow;the huge relief affected the precipitation over the eastern highland,the genesis,development and travelling of the low-value system,and the subtropical high;the terrain east of 105°E had more influence on the eastern event;the relief in east China served as a weakening factor for the highland rainfall.