The formation process of rift basins is influenced by multiple factors, including pre-existing structures, sedimentary material properties, rift phases, and directions. Ultimately, this process results in multiple sets of fault systems with different orientations and scales, leading to the formation of various structural styles. This undoubtedly makes the structural analysis of basins highly challenging. In this study, we replicated the evolution process of the Nanpu Sag since the Dongying Formation, which underwent N-S extension under the influence of multiple factors, through the interpretation of 3D seismic data and comparison with analogue modellings of group structures. The study reveals the following findings: The Nanpu Sag is a result of multiple-phase rifting developed under pre-existing structures. Eventually, it formed a structural pattern of N-S partition deformation, connected in segments from east to west, and vertically deformed within the Minghuazhen formation. The pre-existing paleo-uplift in the southern part of the sag affects the uniformly distributed extensional deformation, while in the northern part, a segmented interconnected mesh-like fault system is formed. Reactivation of pre-existing structures in the southern part leads to the formation of E-W curved en echelon inherited fault systems on both sides. The NE pre-existing fault planes formed during multiple-phase orthogonal rifting processes are important factors restricting the late-stage oriented arrangement of faults. Ductile detachment layers are key material factors that enhance the interaction between faults, transmitting strain initiated from the preset boundary to various parts of basin deformation. They facilitate the connection of isolated faults, forming E-W segmented connected normal fault combinations. The faults accommodate oblique extension caused by pre-existing structures through their own bending.