| To discuss the features and its evolutionary process of the ore-forming fluid of the Damoqujia gold ore deposit, the thermal resource to hold the water/rock reaction, the element migratory behavior during the mineralization, the mineral formation, concentration, deposition of mineral, this paper has carried out the study of fluid inclusions, the numerical modeling in water/rock reaction process and the genetic analysis of the deposit. Furthermore, fruits and conclusions have been got as follows: (1) homogeneous temperatures of the inclusions in no-ore bearing altered rocks are mostly concentrated between 110℃ and 150℃, but those of the inclusions in ore bearing altered rocks are distributed in three space intervals, which are 310℃～350℃, 230℃～ 270℃ and 160℃～210℃, and those correspond to the three ore-forming stages, which are pyrite-quartz stage, quartz-pyrite stage and poly-metallic sulfide stage. Homogeneous temperatures lower than 150℃ corresponds to carbonation stage. (2) During the early ore-forming stage, fluids are with lower-middle salinity. Average density is 0.869～1.018g/cm3. (3) fluid pressure is measured about 260MPa～340MPa by use of CO2-rich multi phase inclusions of the III type. Moreover, while lithostatic pressure is considered uniformly and pressure gradient is 25MPa, mineralization depth will be acquired, about 10Km～13Km. (4) the dominant gaseous component of fluid inclusions is H2O with molar fraction up to 90.915～ 99.346%; And the non-dominant component is CO2 with content lower than 10%; moreover, the other minor components are CH4, C2H6, N2, H2S, et al. that reflects reducing environment. Positive ions of the liquid components are Na+ and K+ in majority, Ca2+ in secondary, Mg2+ in minority; but negative ions are Cl-, SO42- and F- in majority. (5) Heat produced by water/rock reaction may make prominent effects in holding the water/rock reaction. (6)Based on calculation about water/rock reaction, it can be acquired that ore-forming fluids are enriched with Si, K; furthermore, Ti and Al are active elements during the reaction that reflects extremely open environment, however, Mn is inert element. Meanwhile, the volume change of altered rocks indicates more ore-forming fluids involved during the reaction. (7) The results of the numerical simulation of the reaction indicate that quartz, chalcopyrite and sphalerite may concentrate and deposit during the early mineralization, pyrite, galena and gold may deposit together during the middle-late mineralization stage, and carbonate minerals may concentrate and deposit after the mineralization. Furthermore, the property of fluid also change from weakly acidic to weakly alkaline.
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