Abstract: According to systematic sedimentary research on more than 30 wells of Jiyang depression, Later Paleozoic sedimentary in this area was made of sea facies, transitional facies and continental facies from up to bottom. Later Paleozoic sedimentary system has 5 sedimentary systems: barrier lagoon - tidal flat system, carbonate continental shelf system, delta system, peat swamp system and river system. The sedimentary systems were divided 7 facies and 12 subfacies according to the characteristics in rock types, color, authigene and biological fossil. Based on sequence stratigraphy principles and methods, the study on later Paleozoic seismic facies, sedimentary facies and paleogeographic characteristics in Jiyang sag settles the foundation for evaluating Later Paleozoic oil source bed, reservoir and caprock.