Abstract: The uplift and erosion of strata is ubiquitous in sedimentary basins. Restoration of the exact thickness of eroded strata is very important to rebuild the primary sedimentary and structural evolution history, the geothermal history, the history of hydrocarbon generation, expulsion, migration, and accumulation, and also to evaluate the potential of oil and gas resources accurately. Based on structural evolution research in the Northeast Depression of northern South Yellow Sea Basin, according to the practical geological conditions and data, the methods of variance ratio on thickness of reference layers and sedimentary rate are applied to eroded thickness restoration of Eocene Dainan Formation and Sanduo Formation in Northeast Depression. The final result shows that the Sanduo structural movement that happened at the last stage of Eocene leads to the intense erosion of the strata of Eocene Dainan Formation and Sanduo Formation, as well as the two formations above mentioned indicate distinct characteristics in different structural zones of Northeast Depression

Key words: eroded thickness, Eocene, South Yellow Sea Basin, Northeast Depression