Abstract: Based on the normalized monsoon index presented by Li and Zeng (2002), the interannual variation of the South China Sea summer monsoon (SCSSM) during 1948－2006 and its relations with the global atmospheric circulation and sea surface temperature (SST) are studied. The results indicate that there exist significant statistical correlations over large regions between the SCSSM and the global zonal winds, relative humidity and SST, etc. Ten strong SCSSM monsoon years and eight weak SCSSM monsoon years are chosen to identify the differences in atmospheric circulation and SST between the strong and weak SCSSM years. The composite analyses show significant differences in various variables between the strong and weak SCSSM years. Especially in the SST fields, the differences are not only obvious in the Eastern Indian Ocean－the Western Pacific (EIOWP) in summer, but there is also a significant negative correlation between the SCSSM index (SCSSMI) and EIOWP SST in the prior spring which is a substantial relation. The latter could be taken as an indicator of the SCSSM variation.