The Eastern Nanling region is famous for forming quartz- vein type tungsten deposit. The Yanqian tungsten deposit is a newly discovered middle- scale skarn type tungsten deposit in this area. On the basis of detailed deposit geology and metallogenic period study, petrography, microthermometry, Laser Raman spectroscopy analysis and hydrogen- oxygen isotope geochemistry study are carried out systematically for representative minerals of each metallogenic stage in skarn type orebody including garnet, scheelite, quartz and calcite, and quartz in scheelite- wolframite quartz- vein near the skarn. The type of fluid inclusions in the Yanqian tungsten deposit mainly consists of type I fluid inclusion which is two- phase with rich liquid phase type aqueous solution fluid inclusion, type IV fluid inclusion which is three- phase type containing CO2 type aqueous solution fluid inclusion. In addition, a few type I fluid inclusions contain daughter crystal in garnet and quartz. The quartz in scheelite- wolframite quartz- vein contains more type IV fluid inclusion than the quartz in skarn type orebody. In early skarn stage, the temperature is 300~510℃, the pressure is 32~108 MPa, the average fluid salinity is 7.64%, and the average fluid density is 0.69g/cm3. In main metallogenic stage of scheelite (late skarn stage), the temperature is 230~300℃, the pressure is 21~64 MPa, the average fluid salinity is 6.99%, and the average fluid density is 0.87g/cm3. In quartzsulfidecarbonate stage, the temperature is 100~230℃, the pressure is 10~62 MPa, the average fluid salinity is 5.81%, and the average fluid density is 0.95g/cm3. The formation temperature of scheelitewolframite quartz- vein concentrates in 110~320℃, whose upper limit is higher than the temperature upper limit of skarn type scheelite, indicating that the quartz- vein type wolframite has a higher formation temperature. For the Yanqian tungsten deposit, during the evolution of the ore- forming fluid from high temperature to low temperature, the salinity gradually decreased, the density is gradually increasing, and the pressure is gradually decreased. The H- O isotope indicates that the ore- forming fluid is mainly magmatic water, and little meteoric water is involved in the late stage. The metallogenic mechanisms of Yanqian tungsten deposit mainly comprise fluid immiscibility, fluid- surrounding rock interaction, fluid naturally cooling, fluid mixing and pressure decline, espicailly the fluid immiscibility characterized by CO2 loss is important metallogenic mechanism. The petrography, microthermometry and Laser Raman spectroscopy analysis confirm that the quartz fluid inclusions both in skarn type orebody and scheelite- wolframite quartz- vein contain CO2. The coexistence of type I fluid inclusion and type IV fluid inclusion, the coexistence of high salinity fluid inclusion and low salinity fluid inclusion, and a few type I fluid inclusions contain daughter crystal indicate that the fluid immiscibility exists in the ore- forming process of Yanqian tungsten deposit. The ore- forming process is: at the early stage of the mineralization, the magma invades accompanied by separating out the tungsten rich magmatic hydrothermal fluid, strong contact metasomatism occurs between the hydrothermal fluid and the carbonate surrounding rock leading to the release of Ca2+ in surrounding rock and the increase of pH and oxygen fugacity at the same time, largescale cryptoexplosion occurs leading to CO2 fluid immiscibility. The CO2 participates the forming of the alkali metal aqueous solution which can serve as the migration process of tungsten, in addition, the loss of CO2 leads to increase of pH and decrease of oxygen fugacity. The ore- bearing hydrothermal fluid in the early stage of deposit formation is high temperature, high pressure, high salinity, tungsten- rich, calcium- rich, volatile- rich, relatively high pH and slight reductive and then slight oxidative fluid, and a large amount of scheelite precipitates under the condition of decreasing temperature and pressure and increasing pH. Scheelite- wolframite quartz- vein is close to skarn, so the hydrothermal fluid contains Ca2+, but the content of Ca2+ is not enough to form only scheelite, so scheelite and wolframite coexist. The study on the metallogenic fluid of the Yanqian tungsten deposit further confirms the formation mechanism of the skarn tungsten deposit in this area, and is beneficial to the exploration direction of tungsten deposit in the Eastern Nanling region.