Abstract: This study examines the sedimentary facies of the Middle Jurassic Dameigou Formation and their relation with uranium mineralization, providing a basis for the exploration of sandstone-type uranium deposits in the eastern margin of the Qaidam Basin. Surface profile observation and drilling analysis reveal a fan-delta–lacustrine depositional system, with he fan delta developing in the northeastern flank of the Beidatan syncline and lacustrine deposits occupying the southwestern flank of the syncline and the central depression. The fan delta shows a vertical succession of fan-delta plain, fan-delta front, and fan-prodelta, with characteristics of near provenance, large slope, and rapid accumulation, showing a retrogradation sequence and deepening lake conditions. Microfacies identified include distributary channel (gravelly distributary channel), floodplain swamp, underwater distributary channels, interdistributary bays, sheet sands, and fan-prodelta mud, with the lacustrine facies comprising littoral swamps, sand bars, shallow lake muds, and semi-deep to deep lake muds microfacies. Uranium mineralization mainly occurs in the underwater distributary channels of the fan-delta front, where sand bodies develop and have a mud-sand-mud stratigraphic structure. In the humid paleoclimate environment, the sand bodies are enriched in organic matter and carbon debris, and are conducive to uranium mineralization, indicating that these sand bodies of distributary channels microfacies should be priority targets for investigation.