The middle uplift of South Yellow Sea is tectonically one of the most stable areas in the basin, and it has received great concerns since its Lower Paleozoic is a potential hydrocarbon-bearing prospect area. Wavelet analysis method has been used to deal with gravity and magnetic anomalies in the South Yellow Sea to obtain the crystalline basement shape of the middle uplift, and combined with regional geology and seismic section data, some new understandings on stratigraphic distribution features in the middle uplift are described in this paper.