Abstract: Choosing one well separately in eight main sags of the Bohai basin and analysing the subsidence history of each well,we come to a conclusion that the subsidence characteristics of different sags were different. The southern part and the northern part of the basin subsided first, and the central part subsided at a later time. The subsidence center migrated from outside towards the basin center, which reflects the difference of tectonics in different parts of the basin. We made a balanced section analysis for the Liaodong Bay. Combining the subsidence history, we divided its Cenozoic tectonic history into three stages: (a) Rift stage.The time from the Kongdian Formation to the fourth member of the Shahejie Formation is the early rift stage, and the time of the third member of Shahejie Formation is the intensive rift stage; (b) Fault depression stage. The time from the second member of the Shahejie Formation to the first member of the Shahejie Formation is the early fault depression stage, and the period from the third member of the Dongying Formation to the second member of the Dongying Formation is the intensive fault depression stage; (c) Depression stage. This stage lasted from the first member of the Dongying Formation to the Quaternary.