Pyrite is widely distributed in ore-hosting sandstones of the Zhiluo Formation in the Shuanglong uranium deposit in the southern Ordos Basin, northern China. Sandstones from the uranium-bearing stratum was collected to analyze morphologies of pyrite and its relations with uranium mineralization by means of scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS). The results show that colloidal and framboidal pyrite, and pentagonal dodecahedron microcrystalline widely occur in sandstones, and uranium minerals are unevenly distributed around pyrite. According to the occurrences of pyrite, morphologies of pyrite are orderly evolved from microcrystalline, and the formation of pyrite is grouped into four periods. Moreover, the pyrite might preferentially or simultaneously precipitate over uranium minerals. The smaller the diameter of pyrite, the more favorable for uranium enrichment. Additionally, variation trends of U contents are opposed to those of the Fe and S contents as well as the Fe/S atomic ratios. Moreover, the decrease rate of S contents is greater than that of Fe contents. It indicates that S and Fe from pyrite both play roles in uranium mineralization, and the S contribution dominates over the Fe contribution. Additionally, the aforementioned conclusion is also supported by the existences of Fe (III), S, SO32-, and SO42. Compared with carbonaceous debris (CD), pyrite might play a dominant role in uranium enrichment. During the process of enrichment and reduction of uranium by pyrite, CD might provide beneficial reducing environment for precipitation and preservation of pyrite and uranium minerals. The study could provide guide for understanding metallogenic mechanism to some extent.