Abstract: Marine-terrigenous deposits in Bohai Bay is significant for studying marine -terrigenous environmental change, new tectonics, evolutive history of North China Plain and so on, while establishing reliable chronology framework is the base. Here, a detailed paleomagnetic investigation of BZ₂ core (203.57 m) drilled from Tianjin, western Bohai Bay has been carried out. The results show that the core consists of four normal magnetozones which can be correlated to Brunhes, Jaramillo, Olduvai and Gauss, and three reverse magnetozones corresponding to Matuyama and Kaena. Hence, the core began deposition at about 3.18 MaBP. The consistency of sedimentation rate between polarity boundaries show steady subsidence in Bohai Bay since late Pliocene. And the results also have provided reliable chronology framework for studying stratum correlation and marine -terrigenous changes in western Bohai Bay.