Abstract: The Donghai Island is a continental island with special hydrogeological conditions, where the shallow aquifer is separated from the mainland aquifer by the gulf, but the middle and deep confined aquifers are closely linked with the mainland aquifers. For in-depth understanding of the hydrodynamic characteristics of the groundwater in the continental island, the hydrogeological conditions of the Donghai Island is described and the groundwater flow and dynamic characteristics are analyzed. The results show that the Donghai Island is a typical and unique continental island, the shallow aquifer is separated from the mainland aquifer by the Zhanjiang Bay, but the middle and deep confined aquifers are closely linked with the mainland aquifers. There is a uniform distribution of groundwater levels in the middle and deep aquifers in the mainland and the island, and the groundwater in the island flows from south to north and supplies the center of the cone of depression in groundwater levels near the city of Zhanjiang. The shallow aquifer of the coastal and marine areas and the underlying clay layer constitute the protective layers to prevent seawater intrusion into the middle and deep aquifers. The shallow groundwater flow field remained the natural state. The dynamic characteristics of the shallow groundwater in which groundwater level varies with the rainfall are an infiltration/runoff-type. The middle and deep groundwater flow field is controlled by the pumping and groundwater flows from south to north. The groundwater dynamic type of the middle and deep aquifers in which groundwater levels are mainly affected by the impact of the extraction variation is exploitationdynamic type. Near the coastal area, the groundwater dynamic is the tidal effectdynamic type. With the tidal effect, the groundwater level fluctuates periodically.