The Nanpu sag, a hydrocarbon- rich basin located in the eastern part of the North China craton and northern Bohai Bay basin, has been a long- standing debate regarding its tectonic evolution. The primary question revolves around whether the sag formed by extensional faulting was superimposed by strike- slip faulting or if it resulted only from multi- stage extensional faulting. This study addresses this debate by conducting a detailed structural interpretation on eight seismic profiles traversing the Nanpu sag. Our analysis identified NE- SW- striking fault zones characterized by listric normal faults, domino- style normal faults, X- type normal faults, graben- horst structures, and extensional duplex structures, all indicative of typical extensional deformation systems. NW- SE- striking fault zones exhibited left- lateral strike- slip and oblique extension features, mainly serving to accommodate southward movement of the hanging wall blocks along the NE- SW- striking normal faults. The analysis of structural maps of stratigraphic boundaries from different geological periods revealed a distinct migratory pattern of the sedimentary center in the Nanpu sag during the Cenozoic, shifting from NW to SE. Based on these findings, combined with regional tectonic evolution data, we propose a four- stage tectonic evolution model for the Cenozoic Nanpu sag, supporting the hypothesis of multi- stage extensional faulting as the primary driving force behind its formation. This research not only provides valuable insights for future oil and gas exploration in the Nanpu sag but also contributes valuable material for theoretical studies on fault systems.