Abstract: Using ECMWF/WMO daily data and OLR data for the summer of 1984, the influence of convective activities over South China Sea on the north hemisphere mid-low latitude atmosphere are studied through band-pass filtering. Results show that the influence of intraseasonal oscillation of convective activities over South China Sea on the atmosphere circulation over South of China's mainland is seen first in the strength of upward flow ncar Indianesia first, then in the position and strength of subtropical high in West Pacific and therefore influence synoptic condition of South of China's mainland.