Abstract: Quantitative analysis of sandstone clastic composition can provide important basis for provenance and sedimentary basin investigation. Based on the observation and description of sandstone macroscopic characteristics in the field, the ore-bearing sandstones from the Mengqiuer uranium deposit in Xinjiang were studied by optical Microscope and Electron Microprobe. Petrological characteristics of sandstone and occurrences of uranium minerals are discussed. Results show that the compositional maturity index of the sandstone is 0.56-1.08 with an average index of 0.78, indicating low compositional maturity and low structural maturity. The source rock is derived from a mixed recycled orogenic belt transition to the orogenic belt, and finally to the evolution of lithic and orogenic belt transition. The source rocks originated mainly from the Carboniferous-Permian intermediate acid volcanics in the southern margin of the basin and the northern margin of the Nalati, Keguqin, and Bonukenu mountains, as well as the late Devonian-early Carboniferous Dahalajunshan volcanic rocks and Paleozoic granites. Uranium minerals are mainly pitchblende, coffinite, and brannerite with minor adsorbed uranium. The back-scattering image shows that the distribution of uranium minerals is closely related to charcoal, pyrite and rutile.