The Suyunhe Mo deposit,in the western part of the Barluk Mountain, West Junggar, northern Xinjiang, belongs to the Barluk metallogenic belt and consists of three granitic bodies. The orebodies are mainly located in the tuff which contacts with granitic bodies. Mo mineralization occurred in the Early Permain, with the Re-Os model ages of molybdenites being 293. 3 +/- 4. 0Ma similar to 296. 8 +/- 4. 3Ma, the isochron age of molybdenites being 294.4 +/- 1. 7Ma and the weighted average age of molybdenites being 295. 0 +/- 1. 5Ma. Three types of fluid inclusions, i. e., liquid-rich two phases, vapor-rich two phases, and daughter mineral-bearing polyphase inclusions, are present in the Suyunhe Mo deposit. The research indicates that the ore-forming fluids in different granitoids are similar and can be divided into three stages. The early stage, belonging to NaCl-CO2-H2O system, develops all three types of inclusions and is characterized by high temperature, high salinity and high density, with the homogenization temperatures being above 491 degrees C, the salinites being above 58.6% NaCleqv and the densities being above 1. 15g/cm(3). The middle stage, belonging to NaCl-CO2-H2O system, develops liquid-rich two phases and vapor-rich two phases inclusions and is characterized by high-middle temperature, middle-low salinity and middle-low density, with the homogenization temperatures being 240 similar to 443 degrees C, the salinities being 1. 7% similar to 21. 0% NaCleqv,, and the densities being 0. 38 similar to 1. 03g/cm(3). The late stage, belonging to NaCl-H2O system, only develops liquid-rich two phases inclusions and is characterized by middle-low temperature, low salinity and middle-low density, with the homogenization temperatures being 153 similar to 239 degrees C, the salinities being below 9. 6% NaCleqv,, and the densities being 0. 81 similar to.0. 94g/cm(3). The hydrogen and oxygen isotopes of water in quartz inclusions indicate that the early stage fluids were mainly made up of magmatic water, and the middle and late stage fluids consisted of magmatic water and meteoric water. Moreover, the proportion of meteoric water rose with the evolution of fluids. Besides, both the fluid inclusions and hydrogen-oxygen isotopes studies indicate that the boiling and mixing of fluids are the main factors that lead to the deposition of ore-forming substances.