Abstract: The Telaaobaoao uranium deposit is the first super-large uranium deposit hosted in the Lower Cretaceous strata in the northern Ordos Basin. Its sedimentary setting is markedly different from that of the numerous uranium deposits previously studied within the Middle Jurassic Zhiluo Formation. Uranium-bearing sandstone reservoirs in this deposit are notably deficient in traditional reducing agents such as carbonaceous debris and pyrite. The lack of systematic research on reducing media in this deposit has significantly hindered the refinement of uranium metallogenic models and the expansion of successful exploration. In this study, a combination of optical microscopy, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), electron probe microanalysis (EPMA), fluorescence analysis, sulfur isotope analysis, and acidolysis hydrocarbon analysis was employed to identify multiple types of reducing media, including carbonaceous debris, pyrite, hydrocarbon-bearing fluids, and chlorite. Their genetic characteristics were summarized, and hydrocarbon-bearing fluids were determined to be the dominant reducing medium.Specifically, the carbonaceous debris was mainly allochthonous, derived from older strata; the sulfur in pyrite primarily originated from bacteriogenic sulfides and organic sulfides; the hydrocarbon-bearing fluids were sourced from deep coal-, oil-, and gas-bearing strata and migrated into the deposit via faults in its vicinity; chlorite can be subdivided into alteration products of mica and feldspar and authigenic chlorite.Based on the Telao Bao metallogenic model, the types and roles of reducing media during different mineralization stages were discussed: (1) During the sedimentary-diagenetic stage in the early Early Cretaceous, the main reducing media were carbonaceous debris and metal sulfides such as pyrite; (2) In the late Early Cretaceous large-scale reduction stage, the principal reducing medium was deep-sourced hydrocarbon-bearing fluids; (3) From the Late Cretaceous to the Oligocene, during the secondary oxidation–mineralization stage, chlorite further enhanced the reducing capacity of the sandstone reservoirs, ultimately leading to termination of redox-driven mineralization.