Study of sediment grain size composition and distribution paremeters of cores from the Laizhou Bay region, revealed the distribution range of the seawater intrusion channels and showed that they are divided into different types; and that the main seawater intrusion channels in the region are the marine and alluvial-pluvial sand layer in the Post-glacial, Interstadial and last Interglacial. The desertization on the Bohai Sea shelf in the last stage of the late Pleistocene had effect-on the seawater instrusion and the formation of the salt water transitional region and subterranean bittern.