Abstract: This paper presents the composite structure the monsoon depressions , by using composite method to five monsoon depressions over the south China Sea during the monsoon seasoon in the years of 1972-1983. The results show that this kind of monsoon depression in thermal and dynamical structure is different from the monsoon depression in India and tropical depression or wave in middle-west pacific. Its zone of heavy precipitation arc mainly concentrated upon the north-eastern Quadrant of deprossion.