Abstract: This paper analyzed the sedimentary environment of Carboniferous-Permian strata in Ejin Banner and its vicinities for further researches on the sedimentary geology and basin prototype. Field observation was combined with in-house studies in the aspects of lithology, lithofacies construction, paleontologic fossil, sedimentary evolution and sedimentary structure. The results show that sedimentation of Carboniferous-Permian period in Ejin Banner and its vicinities is controlled by Alxa oldland and northwestern marine invasion, lithologic characteristics are controlled by structural units of Carboniferou-Permian strata, and lithologic association is clastic rock + carbonate rock + volcanic rock. The grain sizes of clastic rocks become gradually smaller from south to north: most clastic rocks of shoreland environment lie in the south, whereas most shallow continental shelf and carbonate plateau facies rocks are in the north. It is concluded that the sedimentary environment of Carboniferous-Permian strata in Ejin Banner and its vicinities controls high-quality source rocks and reservoirs.