Several in-situ leachable sandstone-type uranium deposits are hosted in the Shuixigou Group, Middle-Lower Jurassic in the southern margin area of Yili basin. Almost all the geologists think that they are formed by interlayered oxidation genetically. However, the study on the enrichment mechanism of the uranium mineralization is not thorough, and most geologists believe that uranium mineralization results from the reduction and adsorption of the organic matter deposited during the depositional stage of ore-hosting horizons and sulfides formed during the depositional-diagenetic stage to uranium in the interlayered infiltration oxidation water. The researches on the characteristics of oil-gas inclusions and their gas chromatography and acidolysis hydrocarbon indicate that at least one period of petroleum and one period of natural gas migration and enrichment took place in the basin, and the oil and gas in the ore-hosting sandstone of the uranium deposits is originated from the maturated hydrocarbon source rocks of Permian or older strata at depth. On the one hand, oil and gas depleted the oxygen in the ore-hosting aquifer greatly; on the other hand, they also took part in the reduction process of uranium ore-formation, and accelerated the speed of reduction, precipitation, enrichment and ore-formation of uranium. In combination of the study on fault structures of the basin, the authors infer that the oil and gas migrated upward mainly along the EW-striking Dongmanli-Taledi deep-seated fault and the NWW-SEE-striking Hocheng-Tuokai deep-seated fault, and resulted in the formation of strong reduction barrier near the faults so that the spatial distribution of the sandstone-type uranium deposits and occurrences in the basin are controlled by the faults.