mal>Through the interpretation of high-resolution seismic profiles and three drilling holes collected from the mas-microsoft-com:office:smarttags" />Bohai Strait and its surrounding areas, the subsurface strata of the study area were divided into nine distinct acoustic units from the top downward, defined by nine bounding surfaces. The seismic units are correlated well with the cores in the study area. Average acoustic velocities of the stratigraphic units beneath the sea bottom were calculated as basic data for further study of different stratigraphic sequences. With sea level changes in the study area, the acoustic velocity shows a pattern of high-low-high-low with depth in an ascending order.