Abstract: Laoshan uplift is located in the middle of the South Yellow Sea basin.It is a structural unit of the Mesozoic-Cenozoic basin and of very low degree of reconnaissance and research.For a long time,it has not been identified whether sedimentary strata exist below the Neogene.According to recent strategic surveys, a bedded layer has been discovered. On the basis of seismic refection features and integrated gravity-magnetic-seismic inversion,it is inferred that the layer could be marine Paleozoic sediments, belonging to the extension of the Lower Yangtze Paleozoic. This discovery could be of great significance to further promote the survey and study for new oil provinces and new stratification in the South Yellow Sea basin.