Abstract: Because the traps are complicated and the oil-bearing zones are relatively narrow in the stratigraphic oil-gas reservoirs of Qintong sag, there are big differences between the stratigraphic pinchout line obtained from seismic reflection tracing and the actual one, which results in the difficulties in stratigraphic oil-gas reservoir boundary identification and low success rate of drilling. A seismic model obtained from the forward modeling of a stratigraphic pinchout model, the advantages and disadvantages of various attributes in the seismic model are analyzed for the stratigraphic reservoir boundary identification, and the average trough amplitude and average instantaneous phase are selected due to their good recognition effects. The error between stratigraphic pinchout points with different frequency and included angles (i.e. the included angle between unconformity surface and stratum) and the pinchout points on the seismic sections can be obtained through analyses of a series of models at different frequencies. A functional relationship between the included angle and the error of stratigraphic pinchout point is established through matching and then the quantitative calculation of the included angle extrapolation can be realized. The boundaries of stratigraphic traps are characterized detailedly by the integrated use of semiquantitative description of the seismic attributes and quantitative calculation of the included angle extrapolation with seismic forward modeling.