This study investigates interannual variability of sea surface salinity (SSS) in the Yellow and East China Seas (YECS) in relation to ENSO using a global ocean general circulation model. A cyclostationary EOF analysis finds that the interannual variability of the SSS in the YECS is mainly attributable to a Changjiang river discharge (CRD) variability. The CRD variability is linked to ENSO-related precipitation over east China. That is, composite precipitation patterns for El Niño and La Niña years show that when El Niño events occur in winter, rainfall increases over central China in the rainy season of the following years. The increased rainfall in El Niño years results from enhanced southwesterly moisture flux from the South China Sea into central China. The heavy rainfall increases CRD, resulting in SSS decrease in the YECS. This suggests that interannual variability of summer SSS in the YECS is influenced by ENSO via the summer precipitation system over central China.