Interannual variability of the South-Asian high(SAH) establishment over the Indo-China Peninsula(ICP) from April to May and its relation to southern Asian summer monsoon are investigated by using NCEP/NCAR daily reanalysis and out-going longwave radiation(OLR) data from 1979 to 2008.It is found that the duration of the SAH establishment is relatively long(short) in the early(delayed)-establishment years.The upper tropospheric anti-cyclone over the ICP is stronger(weaker) in the early(delayed) years.Before the SAH establishment,the center of the anti-cyclone to the east of the Philippines is to the west of its normal location in the early years.But in the delayed years,there is not a closed anti-cyclone over the western Pacific before the SAH establishment.The time of the SAH establishment is closely associated with the convective development over the ICP.The earlier (later) convective flourish is corresponding to the earlier(later) SAH establishment.The onset of southern Asian summer monsoon in early-establishment years is significantly different from the delayed years.The earlier(later) SAH establishment is followed by the earlier(later) onset of the Bay of Bengal(BOB)-ICP summer monsoon and the South China Sea summer monsoon.Accordingly,the time of the SAH establishment over the ICP plays an indicative role in the subsequent onset of the southern Asian summer monsoon.