The Qianliyan fracture, located in the south of the Qianliyan uplift, is the boundary fault between the north depression and the Qianliyan uplift as a major fault controlling the formation and evolution of the north depression of the South Yellow Sea Basin. Based on the seismic stacking velocity, analysis of reflection characteristics, joint inversion of gravity, magnetic and seismic data, as well as regional geological comparison, the layered formation is interpreted as the Paleozoic marine carbonate and clastic deposits similar to the Paleozoic formation in the Lower Yangtze region. The discovery is significant to the further understanding of regional geological characteristics of the South Yellow Sea Basin.