The interannual variability (IAV) of the intraseasonal variation (ISV) over the South China Sea (SCS) was investigated, focusing on the relationship between the 10--25- and 30--60-day variation. Both ISV activities over the SCS had larger IAV than those of the Bay of Bengal and Arabian Sea. The 10--25- (30--60-) day variation was relatively active when the 30--60- (10--25-) day variation was suppressed in June, July and September. The IAV of the ISV during early summer (June--July) was related to the IAV of the SCS monsoon onset. A late (early) onset was accompanied by active 10--25- (30--60-) day variation. The IAV of the ISV could be divided into early and late summer (September), because there was little persistence between these two periods. Moreover, large-scale circulation anomalies associated with the IAV had different spatial structures in these two periods.