Based on gravity and magnetic data,the authors calculate the gravity basement using constraint inversion method and the magnetic basement of South Yellow Sea with constraint of well and seismic resources.The distribution of Pre-Cenozoic residual basins in South Yellow Sea has been obtained with the calculated residual thickness of Mesozoic and Palaeozoic groups.Some favorable areas of the Pre-Cenozoic are defined through combining the residual thickness and geological conditions for oil and gas accumulation.The results show that the north and northeast parts of northern depression have great residual thickness of Mesozoic group,and the middle uplift and Wunansha uplift have great residual thickness of Palaeozoic group.These areas have Pre-Cenozoic petroleum potential.