The coherent leading modes of precipitation variation over the South China Sea and surrounding area in May and June and their mechanisms statistically were studied

based on the observed data in recent thirty-eight years. The first coherent leading mode shows the similar spatial patterns of precipitation anomalies in May and June. The anomalies in the Indochina Peninsula

the South China Sea and the Philippine Sea are in-phase

which are out of phase with the anomalies in southern China. The first principle component is dominant on interannual time scale. This first leading mode is closely attributed to ENSO events occurred in the previous year. The cold (warm) ENSO events force the persistent anomalous cyclone(anti-cyclone) over the South China Sea and the Philippine Sea in May to June

which eventually leads to a persistent anomalous precipitation over the South China Sea and surrounding areas. The second coherent mode exhibits a rough anti-phase spatial distribution in May and in June. The anomalies in the east part of China are anti-phase to those in the central South China Sea and the Philippine Sea. The second principle component is dominant on interdecadal time scale. This mode is mainly attributed to the advanced interdecadal change of the South China Sea summer monsoon onset affected strongly by the interdecadal change of evolution of low frequent intraseasonal oscillation.