Abstract: In this paper , by using the daily grid point wind data ( 5 °× 5 °) in July-August 1979 which were broadcast by NMC (U.S.A) and other routine-data, we analysed the structure and activity of equatorial buffer zone over east Aaia The results show that equatorial buffer zone over eastAsia is a warm asymme-tric weaiher system in middle and lower troposphere. Negative vor-ticity and divergence downdraft can be found within its domain. And it is found that its activity is different in July and August. The buffer zone usually situates near the equatorial area (1°N-1 °S) during July, whereas it swings to the north of 2°N and will be almost stationary over there during August. Some evidence indicated that this difference is caused by the second seasonal northward jumping of the west pacifc subtropical high. In this period, an obvious adjustment of the longitudinal large-scale circulation would take place.