Based on the latest high-resolution three-dimensional seismic data, the authors carried out the high-resolution well-seismic sequence analysis and seismic sedimentology research for the Lower Ed₂ of Dongying Formation in the BZ3-8 Block, western slope of Bozhong Sag. The results show that on the north and the south sides of the study area, there occurred different sediment provenance systems and facies. The sedimentary facies evolution of the system tracts of the sequence of Lower Ed₂, from LST (rich sand), TST (rich mud) to HST (rich sand), reflects a classical distribution pattern of stratigraphic lithofacies in a sequence stratigraphic framework, which is significant to reservoir and source rock prediction.