Abstract: The geological and geophysical analysis has shown that Xihu sag, East China Sea passed through four prototype basin superimposed and reformed phases in Cenozoic, which are intracontinental tensional fault depression phases from Paleocene to early and middle Eocene, transform continental margin depression phases in middle and late Eocene, intracontinental transported depression phases from Oligocene to Miocene, and shelf margin of back-arc tensional basin phases from Pliocene to Quaternary. The superimposed structure of different prototype basins is related to the tectonic setting and the dynamic setting.