The Middle Jurassic Toutunhe Formation was taken as the main research horizon. Based on the analysis of lithologic features, petrologic characteristics, sedimentary structure, sedimentary system analysis, single well and well- tied sections, the characteristics of uranium mineralized sand body in the Kamuster area are interpreted from the point of view of sedimentology.The comprehensive analysis suggested that there are two types of sedimentary system assemblages developed during the Tutunhe Formation period in the Kamuster area. One is fan delta- lake sediment, the other is braided river delta- lake sediment. Meanwhile, five subfacies are identified as fan delta plainsubfacies, fan delta front subfacies, braid river delta plainsubfacies, braided delta frontsubfacies, and shore- shallow lacustrinesubfacies.Microscopic examination showed that, the sandstone types of the Toutunhe Formation are mainly feldspathic lithic sandstone, followed by feldspathic litharenite complex, lithic sandstone and lithic feldspathic sandstone. The sand is characterized by low compositional maturity and low textural maturity.The distribution of sedimentary facies in the Toutunhe period is characterized by “north braided southern fan”, “large shallow basin, short long fan and gentle slope”. The sedimentary facies of the Toutunhe District Formation have obvious control on the uranium mineralization in the Kamuster area, which is mainly reflected in the following aspects:① the coarse clastic products in the low stand system tract can provide a large host space for uranium mineralization; ② braided channel sand body is the main factor controlling the development of oxidation zone and the enrichment degree of ore body. The stable connection of sand body provides good conditions for fluid migration and mineralization; ③ the special large- scale “mud- sand- mud (coal)” structure is favorable for the development of interlayer oxidation zone sandstone- type uranium mineralization.