The Chengmenshan CuMo deposit, located near the Jiujiang city, Jiangxi Province, is a large comprehensive deposit, which is enriched in oreforming elements of Cu, S, Mo, Fe, Zn, Au and Ag. The deposit is composed of skarn, massive sulfide and porphyrytype ore bodies. Petrographic，microthermometric and Laser Raman Probe studies have been carried out on fluid inclusions (FI) in various kinds of quartz from the Chengmenshan deposit. Five types of fluid inclusions including liquidrich fluid inclusions (FI) (I), daughter mineralbearing FI (II), gasrich FI (III), pure gas FI (IV) and carbon dioxiderich (V), respectively, have been observed. The daughter minerals mainly include halite，sylvite，calcite，anhydrite，pyrite, chalcopyrite and bornite, suggesting that the original magma was important material source of the deposit. This is consistent with the stable isotopic results of previous researchers. Three mineralization stages were recognized in the Chengmenshan porphyry deposit. Quartzmolybdenite mineralization stage (stage I) is associated with Kfeldspar alteration. The fluid inclusions of stage I are characterized by high temperatures (310~486℃) and low to high salinity (\[w(NaCleq.)\]6.2%~41.7%)．Stockwork quartzpyrite mineralization (stage II) may be related to hydraulic brecciation. The fluid inclusions of stage II exhibit medium to high temperatures (251~489℃) and low to high salinity (\[w(NaCleq.)\]1.2%~46.9%). The straight filling veinstyle quartzpyrite mineralization (stage III) developed in phyllic zone may occur in an extensional environment. The fluid inclusions of stage III have medium temperatures (209~386℃) and medium to high salinity (\[w(NaCleq.)\]10.4%~45.7%). From early to late stages, the temperature of mineralization gradually decreased, showing that it is a continuous evolutionary sequence. Boiling had already occurred several times during oreforming evolution and may be the dominated factor for metal precipitation.