GOLD mineralization is closely related to ore-forming fluids. During the evolution of fluids, their naturescontinuously change, and the differentiation of the fluids dominates these changes. Fluid differentiationincludes fluid from melt, fluid immiscibility, gasseparating from fluids and so on. We can understand fluids through inclusions, stable isotope andore-forming experiments. Under the poststage reformation, the composition and phases of inclusionsmight be changed, hence, the initial forming conditions of fluids are difficult to be defined onlythrough the observation of these inclusions. Theexistence of solution phase, gas phase and solidphase (fig. 1) indicate that differentiation occurred During the evolution of fluids, their natures continuously change, and the differentiation of the fluids dominates these changes. Fluid differentiationincludes fluid from melt, fluid immiscibility, gasseparating from fluids and so on. fluids through inclusions, stable isotope and core-forming experiments. Under the poststage reformation, the composition and the phases of inclusionsmight be changed, hence, the initial forming conditions of of are difficult to be defined onlythrough the observation of these inclusions. Theexistence of solution phase, gas phase and solidphase (fig. 1) indicate that the occurred occurred