Due to its large scale, favorablemetallogenic setting and condition sandstonehosted uranium deposit in the Yili Basin in Xinjiang is representative of uranium deposits of this kind. Study of mineralization is of great significance for future exploration and mining. Based on field investigation on sedimentary environment of regional Ubearing strata, with focus on orebearing country rocks, sedimentary sequence of typical sandstonetype uranium deposits in the Yili basin and orecontrolling sequences were analyzed to understand the constraint of clay minerals on uranium mineralization and spatial distribution of uranium mineralization. Systematic study was conducted to analyze clay minerals in orerich sandstone and their constraint on uranium mineralization using uranium geology, energy spectrometer, microscopic structure, scanning electron microscope, geochemistry, and H and O isotope. The results show that clay minerals are distributed widely within oxidation zone and redox zone of main orebodies, especially in strongly altered sandstone, all of which contain higher uranium contents than other sequence, reflecting an internal relation between clay minerals and uranium mineralization. Their relation can be further proved by SEM and energy spectrometer analysis. O and Ubearing fluids passing through sandstone can be absorbed by clay minerals with strong absorption capability and huge surface free energy, forming flake or clumpy clay minerals which contain high U content.Therefore, clay minerals play absorption role in uranium mineralization, facilitating the formation and positioning of orebearing space. Along with sedimentation, tectonic activities and latestage fluid mineralization, clay minerals and other oreforming lithology (orebearing sequence and sources) and structure all controlled uranium mineralization in this area.