The short-range climate prediction of the onset and the intensity of South China Sea summer monsoon are studied. The relationships between the South China Sea Monsoon Index (SCSMI) and the environmental fields, such as 850hPa wind, 500hPa height, SST, OLR, are examined. The possible mechanism of the relationship with the South China Sea Summer Monsoon (SCSSM) is discussed. The anomaly of the SCSMI in winter and the previous environmental fields may be used as a earlier signal to indicate the onset and intensity of SCSSM. Based on the above research results, a concept model is raised for the prediction of onset and intensity of SCSSM. The trial prediction in 1998—2001 got a satisfied assessment.