In this paper, the authors studied quartz veins and calcite veins in the Xiangyangping uranium ore deposit located in the middle segment of Miao'er Mountain pluton. The research samples include quartz veins, calcite veins and breecia ores. They have similar REE patterns showing LREE-enrichment and strong negative Eu anomalies. This characteristic is the same as that of Douzhashan granite, suggesting that most of the uranium came from surrounding rocks. ∑REE and HREE from calcite veins and breecia ores grew with uranium-enrichment process. Carbon oxygen isotope analysis from calcite shows that most of the ore-forming fluid came from the mantle. The uranium-enrichment calcite shows lower δ13C value and high δ18O value, which indicates that CO2 degassing seems to have been the main factor in uranium mineral precipitation processing. From mineralization period to post-mineralization period, δ13C value of calcite grew and δ18O value was reduced; besides, breecia ores had weak negative Ce anomalies. All of these data indicate that meteoric water took part in the process of post-mineralization. The authors built the uranium mineralization model for the middle segment of Miao'er Mountain pluton, and emphasized that multiple phases of mineralization and meteoric water seems to have been the critical factor of forming large orebody in this area.