The Haidewula uranium deposit in the East Kunlun orogenic belt is a newly discovered independent uranium deposit related to volcanic rocks in Northwest China. The discovery of the deposit provides an indication for the exploration of hydrothermal uranium deposits in the East Kunlun orogenic belt. in this paper, the transparent minerals (pink calcite, purple black fluorite and quartz) related to the ore- forming period of the deposit are selected as the research objects. A systematic study of the C- H- O isotopes and fluid inclusions are carried out to find out the source and nature of the ore- forming fluid, and to explore the genesis of the deposit. The results show that the quartz of the ore forming period of the Haidewula uranium deposit is mainly composed of H2O gas- liquid two- phase inclusions, with few CO2- H2O two- phase inclusions; fluid inclusions in calcite vein and fluorite vein contain H2O gas- liquid two- phase inclusions. Pure liquid phase inclusions are occasionally seen, but pure gas phase and solid phase inclusions are not seen in calcite veins. The homogenization temperature range of inclusions in calcite, fluorite and quartz during mineralization is from 133℃ to 187℃ (mean 163℃), from 127℃ to 204℃ (mean 169℃), and from 183℃ to 287℃ (mean 219℃) respectively, and the salinity range is from 1. 40% NaCleq to 7. 02% NaCleq (mean 3. 65% NaCleq), from 0. 53% NaCleq to 3. 06% NaCleq (mean 1. 26% NaCleq), from 7. 17% NaCleq to 17. 26% NaCleq (mean 11. 46% NaCleq). The gas phase composition of fluid inclusions is mainly H2O, and a small amount of CO2. The experimental data of C- H- O isotope show that the variation ranges of δ13CFluid- V- PDB, δDFluid- V- SMOW, δ18OFluid- v- smow values are from 1. 59‰ to 1. 00‰, from 71‰ to 63‰, from 0. 03‰ to 3. 72‰ respectively, indicating that the ore- forming fluid is not a single source, and may be a mixed source of atmospheric precipitation and magmatic water. In addition, the precipitation of pitchblende is mainly due to the changes in physical and chemical conditions caused by the interaction between fluid and hosted- rock, as well as fluid boiling/CO2 degassing, leading to large- scale unloading and precipitation of the pitchblende and other uranium minerals.