Abstract: Marine transgressions and regressions occurred frequently along the Bohai Bay during the Quaternary period due to sea level changes. The stratigraphic and chronologic data from previously published cores suggest that the early-middle Pleistocene marine transgressions are limited in small areas, and uncertainties still remain with its existence. Large-scale transgressions occurred mainly in MIS5, MIS3 and MIS1 of Late Pleistocene. It is believed that the transgression was caused by sea-level rises induced by interglacial climate under a long-term tectonic background of subsidence. During the period of MIS3, due to the effect of topography, which was higher in west and lower in east, shallow marine deposits were formed in the basin with transitional and continental deposits formed along the coast with gradual sea level rise. Some researchers argued that that transgression deposits formed MIS3 in the inland area may have been eroded during the following glacial. Further researches are required to reveal the cause.