Sensitivity experiments to investigate the role and importance of the Indo-China Peninsula (ICP) heat fluxes (sensible and latent heat fluxes) on the South China Sea summer monsoon (SCSSM) onset and its subsequent evolution have been carried out using a regional climate model. Two sensitivity experiments have been conducted: cutting off the sensible heat flux (noted as IChfx) and latent heat flux (noted as ICqfx).Results show that by cutting off the underlying heat flux of the ICP, the precipitation decreases and low-level geopotential height increases over the local regions as well as the remote regions of the East China Sea, southern Japan, and western North Pacific. The westerly (easterly) zonal winds at 850 hPa (200 hPa)are generally weakened in May and June, especially before and during the onset of the SCSSM towards the end of May.It is worth noting that although the observed sensible heat flux is only about 1/3 of the latent heat flux,the differences between the control run and each of the two sensitivity experiments are comparable.