Abstract: The south slope zone of the Laizhouwan Sag in the late stage has been reformed in many large-scale tectonic movements, resulting in the unclear appearance of the original basin and the unclear distribution of the sedimentary system. Based on the tectonic evolution analysis as the main line, through seismic interpretation, sound wave time difference method and trend thickness method, prototype basin at the sedimentary period and its configuration relationship have been recovered in the lower third sub-member and the fourth member of the Shahejie Formation at the early paleogene, and the planar distribution and controlling factors of different sedimentary system have been cleared. Study showed that:(1)At the sedimentary period of the fourth member of the Shahejie Formation, the whole south slope zone of the Laizhouwan Sag were lifted and dropped due to block differences caused by fault extension, in the west three east-west spreading fault trough were formed by two groups of east-west trending faults and the east and south areas were the uplift areas of the Weibei salient.The early faults resulted in the palaeogeomorphology differences in the east and west. (2)At the sedimentary period of the lower third sub-member of the Shahejie Formation, the whole south slope zone went through rapid settlement and the west part was uplifted by the differences between the east and west faults, forming a local highland. Part of the eastern Weibei salient submerged in water later, forming broad platform. (3)Different provenance supply systemcontrolledthe differential distributionin Fan delta and braided river delta of the fourth member of the Shahejie Formation. Geomorphology together with the provenance supply differentiation controlled the development of lacustrine carbonate rocks and weathered eluvial facies and their vertical distribution in the lower third sub-member of the Shahejie Formation. The development and distribution of sedimentary systems have an important response relation to basin prototype.