Tectonism and climatic condition are the most principal factors controlling the formation and evolution of the lake-basin.It is because of their combined action that a great variety of lakes and their sedimentary constructions in ancient and modern,Chinese and foreign are brought about.In this paper,the varieties of paleogeographies at different stages during early Tertiary in the Jiyang lake-basin are reconstructed,mainly based on paleotectonics,paleotopography,the lower Tertiary deposits,paleontology,paleoecology and the results of minor elements and isotope analysis,also with the aids of sporo-pollen data from other researches.In the early Tertiary,NW-SE trending regional tensile stress field and a series of mantle bulges such as Bohai Gulf mantle bulge with triple junction consisting of lower Laohe,Huanghua and Jiyang was formed in Eastern China,because the Pacific plate was subducted northwestwards and the Eastern Asian continental plate margin crept oceanwards.For this reason,the research district became the southern branch of the Bohai Gulf continental rift basin,in which the evolution had mainly gone through four stages including spreading and faulting-down from initial(Kongdian Epoch of early Eocene) to intense(from Shahejie-4 Epoch of middle Eocene to Shahejie-2 Epoch of early Oligocene).