Objectives：The mengqiguer uranium deposit, Ili Basin, was interlayer oxidation zone type uranium deposit. Although its metallogenic fluid was studied systematic by predecessor, the problem about its source still exist, especially about the internal relation between metallogenic fluid and alteration characteristics and uranium mineralization. In this article, we will find out the source of metallogenic fluid, the relationship between metallogenic fluid and diagenetic alteration and uranium metallization. Methods：In order to researching the source of metallogenic fluid and the relationship between metallogenic fluid and diagenetic alteration and uranium metallization, the methods of polarizing microscope, scanning electron microscope, electronic probe was comprehensively utilized to analysis alteration characteristics of sandstone in the orebearing layer systematically and the stable isotope of alteration mineral about ite, carbonate cement, pyrite in sandstone of orebearing was studied.  Results：The diagenetic alteration characteristic relating to sandstonetype uranium deposit mainly include clayzation, carbonation, silication and metal mineralalization; the δD（aq）VSMOW and δ18OVSMOW of its metallogenic fluid is varies from -93‰ to -48.3‰, -10.3‰ to -5.1‰ respectively, the δ13CVPDB and δ18OVSMOW of its carbonate cement from sandstone in orebearing is range between -10.9‰ and -7.2‰, 17.6‰ and 24.9‰ and the δ34SVCDT is range from -17.3‰ to 1.2‰ respectively.  Conlusions：The above characteristics reveal that the metallogenic fluid of Mengqiguer Uranium deposit is mixed fluid which consists of surfacewater stemming from meteoric waters (inorganic) and organic acid, reducing gas (CBM) originating from coal evolution; As a result，the effect of diagenetic and uranium mineralization was result from reciprocity of organic — inorganic fluid and fluid—rock.