Geological conditions of Bohai Strait is complicated. Meteorological conditions, topography, stratum lithology, geological structure, earthquake activity are directly related to the Bohai Strait cross-sea construction successful or not. Adopting the research method, a lot of engineering geological and hydrogeological data of the bohaistraitwere collected, and detailed analysis has been carried on, the regional stability evaluated. The bridge is not disadvantage of the all-weather horoughfare, for thick fog, high wind and the average gale in year days up to 67.8 days in Bohai Strait;because there are some islands and islets what keep a line along the longitude, the joining islands are choosed for the Bohai Strait cross-sea engineering construction to reduce the difficulty and cost of construction. There are the poor stability Quaternary stratigraphic and third strata mainly basalt, large pore structure,very uneven distributed and up to 70 m cover, and these two sets of strata have great influence on theoption of buried depth of the tunnel. To line of Penglai—Lvshun, there are not active faults in construction site, and the formation of relatively stable. These work can provide reference for the Bohai Strait cross-sea construction.