Abstract: As a kind of valuable resource, saline groundwater is widely distributed in the Pearl River delta, which is less studied. Based on primary data obtained in the national geological survey program, we implement a targeted study on origin and evolution of the saline using sedimentology and hydrogeochemistry. We find that the saline groundwater is originated from paleo-seawater and highly related to retrogradation process in the early period of middle Holocene. Seawater originally included in less permeable strata leaks to underlying confined aquifer by compaction. Saline groundwater is possibly influenced by lixiviation water in formation process. Mineral dissolution and ion exchange may contribute to the salinity enrichment.