Abstract: Drawing on the idea of velocity model building in pre - stack depth migration processing, the followings have been carried out during fine interpretation of velocity spectrum. The relationships between velocity spectrum and strata and seismic reflectance horizons have been thoroughly analyzed on the basis of comprehensive understanding of regional geologic features. The interpreted horizon markers have controlled the main points of velocity change during velocity spectrum interpretation. Fine interpretation of velocity spectrum has been accomplished according to energy distributions of the shallow horizons and mid - deep horizons in velocity spectrum. The results of velocity spectrum interpretation with this method are better than that of the other methods. It has been verified by inversion without well control in Guan 11 block in Dongying sag.