Abstract: Saltwater intrusion in the Pearl River estuary during dry season seriously affects the freshwater supply security of cities in the Pearl River Delta. The joint regulation of upstream reservoirs to increase downstream flow is one of the effective measures to deal with saltwater intrusion. To meet the demand for the discharge of Sixianjiao section for suppressing saltwater and replenshing freshwater, a regulation model for the key reservoirs in the Xijiang and Beijiang River basins was established to study the water replenishment strategy under different discharge conditions. The results have great significance for alleviating freshwater supply problem caused by drought and saltwater intrusion in the Pearl River Delta, and can provide reference for real-time optimal dispatch in the future.