|Abstract:A series of sandstone/mud-type uranium deposits have been proven within the Erlian Basin in the last 20 years, thus the basin is an important uraniferous basin in China. Weijing granite, located in the Bayinbaolige uplifted zone, the northwest of the Erlian Basin, is a multi-staged granite (from Hercynian to Yanshanian). Its distribution area is large (>1000km2), and surrounded by several uranium deposits. In order to study the relationship between the Weijing granite and uranium mineralization, field geological investigation has been conducted, and a series of samples of Weijing granite and sandstone of Saihan Formation have been taken. By means of microscopy, Weijing granite is medium to coarse-grained biotitic porphyritic-like granite. Petrologically, sandstone of Saihan Fm consists mainly of quartz, feldspar ( plagioclase and potash feldspar), and lithic fragments sourced from ganites. The analytic results of REE indicate that the material sources of ore-hosting sandstone are sourced also from Weijing granite. Pb isotopic analysis demonstrates that the primitive uranium content (U0) of Weijing granite is high, ave. 15.17×10-6, whereas, the average lost uranium amounts to -45.47%. Like the granite, the oxidized sandstone of Saihan Fm is lost obviously in uranium, ave. 41.42%. But the reduced sandstone of Saihan Fm is rich in uranium, ave. 66.8%. Hence, all studies show that Weijing granite provides both sediment sources for sandstones and uranium sources for uranium mineralization in sandstone in Erlian basin. From apatite track analysis, the Weijing granite and its adjacent area were rapidly uplifted during Late Cretaceous to Eocene (76.7 ~ 53.8Ma). This tectonic activity is accordant temporally to the uranium mineralization in sandstone and mudstone. Conclusively, the uplift trigged the uranium mineralization.