Wan'an Basin is a typical strike-slip extensional basin in multi-plate superimposed area of southern South China Sea. Due to the complex geological conditions and lower research degree in China, the structural characteristics of major depressions are lack of targeted research, which limited the understanding of the potential and distribution of oil and gas resources. Based on fine seismic interpretation, the tectonic transformation change and its unconformity characteristics, fault systems and tectonic evolution characteristics, and the control of structures on oil and gas distribution are analyzed in Wan'an Basin. T100 (pre Cenozoic basement interface), T60 (Neogene bottom interface), T40 (upper Miocene bottom interface) are the key geological interfaces of structure and sequence in different periods with response to regional tectonic events. The tectonic evolution of Wan'an Basin can be divided into rifting period including two episodes (T100-T60, T60-T50), inversion period (T50-T40), and post rifting thermal subsidence period (T40-). Faults are mainly developed below the T40 unconformity. The most developed NE, NNE faults control the tectonic pattern of Wan'an Basin. As a basin controlling fault, Wan'an fault has strong early activity in rifting stage and weak late activity in the thermal subsidence stage, and has strong activity in the middle, followed by the north and south in space. Under the transformation of fault, the sag has a multi-depression structure, which reflects the characteristics of typical rift blocks and structural evolution differences. Based on the spatial and temporal distribution of typical oil and gas fields in Wan'an Basin, it is concluded that source rocks and their thermal evolution control the plane distribution of oil and gas fields, and uplift belt, slope belt and reverse belt around the favorable middle sag control the spatial distribution of oil and gas fields. On the whole, it has the oil and gas enrichment laws of preponderant accumulation in the pre bulge zone, three dimensional accumulation in the slope zone, and compound accumulation in the central inversion zone.