Abstract: The overlap?erosion oil reservoir is the main type in shallow overlap?erosion belt of Chunhui oilfield in Junggar basin. Accurate determination of the stratigraphic overlap?erosion line is of great significance for guiding oil?gas exploration here. It is indicated by forward modeling that there exists an extrapolating distance between the seismic overlap?erosion line and the real line constrained by seismic vertical resolution, and the distance decreases with stratigraphic inclination angle increasing, increases with stratum velocity increasing and decreases with seismic frequency increasing. Therefore, this paper establishes the extrapolating equations suitable for the studied area and determines accurately the positions of the overlap?erosion line