Abstract: Preliminary result has indicated that the age of the second marine layer in the southern coastal lowland of Bohai Bay is > 43.5ka BP. Recently, six boreholes have been drilled in the coastal lowlands north of Cangzhou and north of the Haihe River, and two new profiles perpendicular to the modern shoreline were then established. Combined with the lithostratigraphy, foraminiferal assemblages and AMS ¹⁴C dating results, the second marine layer in these cores has been identified spatio-temporarily. The dating results of 9 samples collected from the second marine layer show that the ages are all older than 43.5ka BP. Up till now, 21 AMS ¹⁴C ages collected from the second marine layer in 10 boreholes, given by the authors, indicate that the widely distributed second marine layer was formed in the early MIS 3 or MIS 5 stages rather than 23~39ka BP as previously believed.