Based on the NCEP/NCAR reanalysis data, outgoing long-wave radiation(OLR) data and precipitation observed by satellite and meteorological stations, the convective activity, general circulation and precipitation before and after South China Sea summer monsoon(SCSSM) onset of 2007 are analyzed. Results show that the convective heating first appears in the east coast of Bay of Bengal, then extending to South China Sea in 2007. Meanwhile, the subtropical high withdraws eastward and northward, and SCSSM breaks out in the last two dekads of May(the 29th pentad) in 2007. After the monsoon onset, South China Sea area is controlled by southwest air current, and the meridional temperature difference and wind shear reverse in Asian mid-low latitudes areas. During the SCSSM period of 2007, the enhancement of water vapor transportation and monsoon surge lead to the precipitation increase in eastern China.