Upon previous researches， insights have been gained through detailed observation of 12 new outcrop sections and cores （mostly gathered after 2016） from 31 typical wells on the perihhery of Tarim Basin as well as fine interpretation of sedimentary facies in 82 wells together with the interpretation and seismic facies identification from 188 two-dimensional seismic lines and three-dimensional seismic data in five acreages focusing on the Ordovician in the Tarim Basin. Firstly， sedimentary facies types and features are determined by observing single outcrop sections and analyzing drilling data of single wells. Secondly， sedimentary facies changes are mapped through correlation between outcrop sections and well profiles. Thirdly， facies boundaries are delineated based on seismic facies types and their planar distribution determined through seismic interpretation and tracing. Finally， the lithofacies paleogeography during the deposition of each formation of the Ordovician are mapped to reveal their paleogeographic and sedimentary patterns. The results show that the sedimentary period of the Penglaiba-Yijianfang Formations in the early Ordovician is rather a pattern of "one platform with two edges and two basins" than a pattern of "a west platform coupled with an east basin" that as previously determined. The Ordovician carbonate platform is suggested to have evolved from a unified carbonate platform to multiple platforms after differentiation and to the final extinction. Based on these understandings， three sedimentary filling models are established for the evolution of the Ordovician， i.e.， the early single platform - coexisting gentle slope and steep slope edge - basin， the middle multiplatform - multiple edge - multiple basin and the late marine environment with terrigenous clastic input.
