Abstract: By using the HIRS-TB12 data observed from NOAA satellites and comparing with the NCEP/NCAR data, we find that the subtropical high in Northern and Southern Hemispheres have different features of temperature, moisture and vertical motion. When the South China Sea high and the Arabia high weaken rapidly and the pentad-mean HIRS-TB12 of both areas are less than 200 W/m², the South China Sea monsoon and the Arabia and the Bay of Bengal monsoon come to onset respectively. The relations of drought/flood in East China with the South China Sea monsoon onset data and intensity, the variation of the position and intensity of the subtropical high in both Northern and Southern Hemispheres have also been discussed.