Abstract: Radiocarbon datings indicate that the marine deposits at the depths of 23-40m along coast of Bohai Bay were formed sonn after the slope of the peat development (32000 -22900yr. BP), which can be comparable with the sub-interglacial periods of the last glacial epoch(about 44000-29000yr. B P) and is agreeable with the high sea level period over the whole world in the late stage of the Late Pleistocene (about 35000-23000yr. BP).The lacustrine-swamp peaty deposits or puddly deposits of various thickness have a wide distribution at the depths of 12-16 m beneath the ground surface and 5-6m depth below the Bohai sea floor with 20-30m water depth. In the light of the radiocarbon datings the peaty deposits concerned can be largely placed in Early Holocene (about 10000-8000yr. BP) and named as Lijiabao. Formation, it can be correlated with the Purangdian Formation of Liaonan region. Above the peaty deposits are in succession developed a series of marine sediments. From the radiocarbon datings of shelly bed and oyster-bearing bed in offshore and epicontinental sediments from the underlying peaty deposits and marine sediments, especially from the top of the latter, the marine sediments may be formed in Middle Holocene (about 8000-2500yr. BP) and named as Hou-chengzhuang Formation which can be correlated to the Dagushan Formation of Liaonan region. Most of recent deposits near ground surface are of fluvial facies, and the peaty deposits are also found in the swamp or the ancient river course. From the radiocarbon datings it can be suggested that the marine sediments beyond the Ⅱ chenier ridge along the western coast-of the Bohai Bay and the continental sediments within the Ⅱ chenier ridge both have the age less than 2500yr. belonging to the Late Holocene and correlating to the Zhuanghe Formation of Liaonan region. It is referred to the Qikou Formation.The lithological changes happened in this region and the datings of Holocene deposits indicate that there has been a transgression in Holocene period and sea water arrived at the studied region 7000 years ago. Later on the transgression reached its maximum in the region 6000-5000 years ago when many regions such as Leting, Luannan, Ninghe, Tianjin, Cangzhou, Huanghua and Haixing along the coast of the Bohai Bay are submerged or affected by sea water. About 4000 years ago there was started a regression forming successively the Tongju-Qianmiaozhuang (4700-4000yr. BP), the Zhang-guizhuang -Changzhuang (3800-3000yr. BP), the Baishaling-Nigu-Qikou(2500-1500yr. BP) and the Chengtougu-Dagu chenier ridges (600-500yr. BP).