Abstract: The uplift and erosion of strata are ubiquitous in sedimentary basins. Restoring exact thickness of the erosion is very important to rebuild rationally the histories of initial deposition-tectonic evolution, geothermal, hydrocarbon generation, expulsion, migration and accumulation, and also to evaluate accurately the potential of oil and natural gas resources.On the basis of researches on tectonic evolution in northeast depression of the South Yellow Sea basin and according to practical geological conditions and present information, the method for thickness variance ratio of reference layer and sedimentation rate was applied to the eroded thickness restoration of Eocene Dainan formation and Sanduo formation in northeast depression. The final result suggested that the Sanduo tectonic movement which occurred at the last stage of Eocene, resulted in the intense erosion of Eocene Dainan formation and Sanduo formation,and these two formations indicate distinct characteristics in different tectonic zones of the northeast depression.