Abstract: Fluid performs as both medium and agent. The fluid action runs through the whole mineralizing progress of endogenetic gold deposits.Different types of gold deposits from different regions share a similar original ore-forming fluid, i.e., the C-H-O system derived from upper mantle or lower crust, rich in SiO2, volatile components and metallogenetic elements. During the migration from deep to shallow position, the original ore-forming fluid is changed in physicochemical characters and composition by the factors of rock formation, mixture of fluids from strata and water/rock reaction, forming a metallogenetic fluid that leads to gold mineralization. The main reasons for the precipitation of ore material (such as Au) in metallogenetic fluid are boiling of fluid, escaping of volatile component from fluid, separation of fluid phases, mixture of different types of fluids and hydrothermal alteration (water/rock reaction).