Abstract: In order to study the uranium source and its geological significance of the Dongsheng uranium orefield, the geochemistry, electron probe and stable isotopes of ore body and country rock from the Nalingou uranium deposit are selected. The results indicate that the original uranium content of orebody and mudstone is separately 212.45×10^-6 and 41.34×10^-6, showing strong preenrichment in the process of syngenetic sedimentation. The debris mainly comes from the adjacent Yinshan Precambrian basement, a few from late Paleozoic acid magmatic rocks, and the uranium in the process of pre-enrichment are mainly from the erosion source area of the northern basin. The REE distribution patterns of the uranium ore body and country rock is generally the same, with individual δEu positive anomaly, enrichment of LREE, and the same source of uranium. The δ¹³C_V-PDB and δ¹⁸O_SMOW values of the ore bodies are -9.7‰ and 18.9‰ respectively, and the δ³⁴S_v-CDT value of pyrite is -27.46‰, indicating that they experienced a strong organic geological process. Coffinite occur around the charcoal and scattered pyrite, and were cut through by colloidal pyrite. Uranium is enriched after diagenesis. It is believed that the pre-enrichment of uranium in the process of syngenetic sedimentation is the direct and importont source of uranium mineralization, and Dongsheng uranium ore field is the product of diagenesis of Zhiluo Formation.