This paper analyzes the hydro-geologic characteristics of HZM bridge tunnel according to the hydrological and meteorological data, chemical analysis of water, pumping test, CPTU, topography, stratigraphy, as well as soil’s physical and mechanical properties of the HZM Bridge tunnel area. The result shows that the field of surface water is sea water, the loose stratum pore water is weak-pressure water, and there is a direct hydraulic connection between bedrock fissure water and loose stratum pore water. The region is typical delta estuary zone and its engineering hydrogeological characteristics are unique, so it can supply experience for other similar delta estuary zone engineering.