Abstract: Parameters of organic matter(Cy),pyrite(FeS₂),magnesia (MgO),phosphate(P₂O₅),iron oxide(Fe₂O₃,FeO) and Fe³⁺/Fe²⁺ play an important role in the formation of in-situ leachable sandstone-type uranium deposits.Comparative study of parameters of sandstone of the primary zone in the ore target in the no rthwestern part of the Junggar basin and those of sandstone of the primary zone in the 512 uranium deposit on the southern margin of the Ilibasin indicates that a pronounced inherent shortage exists for the potential of uranium mineralization in the sandstone of the primary zone in the northwestern part of the Junggar basin.Changesin sedimentary facies and sedimentary environment are the cause re sponsible for the great difference in the aforesaid parameters.Additonally,the authors point to the direction in future mineral exploration in the area.