At present, uranium exploration and related genetic studies have rarely been conducted in Jabal Twalah, Kingdom of Saudi Arabia. A case study is carried out for identifying mineralization characteristics and genesis of newly discovered pegmatite- hosted uranium- thorium mineralization and hydrothermal uranium mineralization in alkaline granite. Zircon U- Pb dating results show that U- Th mineralized pegmatite and wall rock alkaline granite were formed simultaneously at 638. 6±3. 2 Ma and 632. 5±1. 5 Ma, respectively. Combined with a series of analysis methods including petrography, geochemistry, and SEM- EDS, mineralized pegmatites were demonstrated to be strongly enriched in U, Th, rare earth elements, and rare metals, and suffered from post- magmatic hydrothermal alteration. However, U and Th are still hosted together in accessary minerals rather than occurring as independent uranium minerals. Mineral assemblages in mineralized pegmatite are characterized by magmatic minerals, such as rutile, zircon, bastnaesite, xenotime, thorite, etc. For the epithermal granite- hosted uranium mineralization, uranium minerals sampled from the superficial specimens occur as kasolite and uranophane, while gang minerals comprise hematite, fluorite, quartz, and minor calcite. The granite- hosted uranium mineralization is controlled by high uranium- bearing granite, strongly silicified structural zone, as well as late intrusive felsic- mafic dykes. Thus, uranium targeting in the future should focus on strongly silicified fracture zones, and their turning zone or intersection with dykes.