Abstract: A breakdown process and structure characteristics of the monsoon trough over Asia in July 1982 was discussed in this paper. It is found that during the period of the monsoon prevailing over Asia in the summer, when the subtropical high in the western Pacific moves eastward and the monsoon depression which originated in the Bey of Bengal travels westward, the monsoon trough in the region of Iudo-china Peninsula and South China Sea may be broken. So the monsoonal southwes-terlies in the tropics flow northward and the band of the plum rairs shifts northward. The rainfall increases. According to the vertical structure of the zonal wind in the monsoon area, we may interpret the reason of the following fact:a large amount of the monsoon cloud clusters or the monsoon depression develop frequently in the vicinity and the southern extensive area to the monsoon trough over India and ludo-china Peninsula The.strong tropical cyclones or the solenoidial cloud systems of the typhoon often occur in the vicinity of and the northern region to the monsoon trough over the western Pacific The conditions in the region of the South China Sea are intermediate Sometimes the weak typhoon may |originate here. Sometimes there is a great deal of the monaoon cloud duster in the area.