This study explores the effects of the Changjiang river discharge (CRD) on the density stratifications and associated sea surface temperature (SST) changes using a global ocean general circulation model with regional focus on the Yellow and East China Seas (YECS). The regressed field of SST on the CRD and cyclostationary EOF analysis find that the CRD contributes to maintaining warm sea surface in August. This warming is attributable to the formation of CRD-induced barrier layer, which tends to enhance stratification at the mixed layer base, thereby reducing both vertical mixing and entrainment cooling. The SST difference between the composites of flood and drought years confirms that the surface warming is related to surface freshening by the CRD. This result suggests that the CRD-induced barrier layer is an important contributor to the surface heat budget in the YECS in summer.