The Cenozonic tectonic evolution of Laizhouwan Sag is detailed studied with the seismic and drilling data of this sag and around it, several means are used in this research, such as analysis of stratigraphic distribution, tectonic reconstruction, analysis of single well’s burial history and subsidence history. Through the study of stratigraphy and tectonics, it is found that two periods of tectonic stress field turning existed during Cenozonic, which play an important role in the sag’s forming and evolution, and they happened during Sha 3 period （40Ma around）and between Eogene and Neocene（20Ma around）. Thereinto, the former period of tectonic change, is simultaneous with another tectonic event that the movement of Tanlu fault changed from left-lateral strike-slip to right-lateral strike-slip, and that show both of them may have a certain inner relationship; studied in basin type shows that Laizhouwan sag is not a typical right-lateral strike-slip pull-apart basin, while it is a rifted basin which mainly controlled by the extensional regime and also affected by the strike-slip regime at the same time, concretely speaking, it is a faulted basin which maybe under the affection of the left-lateral strike-slip before Sha 3 period, and then it maybe became into a faulted-depressed basin which under the deformed of right-lateral strike-slip; after the comprehensive analysis, the Cenozonic tectonic evolution of Laizhouwan sag is divided into four stages: Rift stage (from Kongdian period to Sha 3 period ); Fault depression stage(from Sha 2 period to Dongying period); Depression stage (from Dong 1 period to Guantao period); New tectonic movement- effect stage(from Minghuazhen period to now).