The third Member of the Paleogene Shahejie Formation is the primary target in petroleum exploration of the Shen84—An12 block which is located in the Damintun sag, Liaohe depression. Based on a compilation of data from drilling, core, well logging, and related analytical experiments, multiple methods were used to infer the characteristics of the provenance system, such as analyses of potential provenance direction, detrital composition, light and heavy mineral assemblages and variation of coarse/fine-grained sediment planar distribution.The fundamental principles of sedimentology were applied to investigate the sedimentary facies and their evolution in the third Member of the Paleogene Shahejie Formation. The results show that the third Member of the Paleogene Shahejie Formation is mainly derived from the recycled sedimentation of the Neoarchean to Paleoproterozoic metamorphic basement, and the Mesozoic intermediate-acidic igneous rocks formed in various tectonic movements, and was subsequently influenced by the Late Mesozoic mantle-derived material. We inferred the primary provenance directions are mainly north to east and northeast to southwest. The E s 43Ⅱ and E s 43Ⅰ oil formations from the third Member of the Paleogene Shahejie Formation were deposited in the shallow-water fan delta front, and were further divided into underwater distributary channel, underwater distributary bay (sand-rich) and underwater distributary bay (mud-rich) microfacies. The paleo-lacustrine environment in the research area changed the water depth from shallow to deep during the sedimentation of the E s 43Ⅱ to E s 43Ⅰ, while the distribution range of the underwater distributary channel and the underwater distributary bay (sand-rich) decreased, and the underwater distributary bay (mud-rich) gradually increased.