Abstract: The study of the distribution characteristics of abnormal high pressure reservoirs in Dongpu sag in Bohai Bay basin shows that the measured abnormal high pressure in this sag can be divided into source rock abnormal high pressure and reservoir abnormal high pressure. The main reason of the former is the late hydrocarbon generation, and that of the latter includes effective plugging effect caused by salt or shale, its oil and gas saturation and maturity. The secondary hydrocarbon generation served as the material basis for its late hydrocarbon accumulation in condition of deep abnormal high pressure. Such a reservoir is characterized by late formation time, short oil?gas migration distance, high gas?oil ratio and big reservoir pressure factor, etc., and generally distributed in slope zone and sides of an uplift belt, with buried depth of less than 4 300 m