In recent years, significant advancements have been achieved in uranium (U) prospecting within the Lower Cretaceous strata of the southwestern Ordos Basin, China. U deposits have been unearthed in Zhenyuan and Pengyang County, predominantly found within the Cretaceous sandstones of the Luohe and Huanhe formations. These ore-bearing strata primarily originate from arid environments, characterized by a deficiency of organic matter (OM). This deposit type manifests within lenticular, gray sandstone interbedded within red sandstone. Its genesis markedly diverges from oxidation-reduction sandstone-type U deposits, yet systematic studies on the properties of ore-forming fluids, particularly their sources and contributions to U mineralization, remain lacking. Core observations were conducted, and representative samples were collected for laboratory analysis. This study discerns the characteristics of ore-forming fluids within the U-bearing sandstone and deliberates the source of these fluids and their impact on U mineralization. Results indicate an abundance of flow-patterned, OM-rich U ores, derived from the deep mudstone rocks of the Yanchang Formation. The ore-forming fluids, characterized as OM-rich and low-temperature (130 to 180 degrees C) hydrothermal fluids, originate from fluid discharge within the source rocks. Subsequently, ore-forming materials dissolve within these OM-rich fluids and migrate towards the oxidized sandstone in shallower regions. Significant changes in temperature and oxygen fugacity lead to fluid differentiation or cracking, facilitating U precipitation into U ores. The characteristics of Cretaceous U mineralization in the study area are consistent with the exudative model of sandstone-type U metallogenesis.