Learn more about the forming path of magmatic—hydrothermal system of rare metal granite and its ore-forming process.Methods:Taking Limu granite,a typical representative of rare metal granite in South China,as a case of study,come to understand the forming path of magmatic evolution through a in-depth study of petrography on vertical zoning of the granite.Then,by correlating magmatic evolution with geological characteristics of mineral deposit,deduce how the magmatic—hydrothermal system come into formation and ore-forming process.Results:①In addition to crystallization,there is also large-scale gas—liquid fractionation in magmatic evolution,and the formation of magma—hydrothermal fluids is mainly related to the gas—liquid fractionation.Therefore,the magma—hydrothermal fluid is not the residual magma solution in the traditional sense.②The forming path of magma—hydrothermal fluids is：large-scale gas—liquid fractionation takes place in the water-rich magma during its emplacement,forming gas-rich fluid and new remain molten phase magma.Then the gas-rich fluids rise to three different spaces where,they will undergo the second time gas—liquid fractionation as decrease of temperature and generate the residual gas- rich fluids which is the so-called magmatic—hydrothermal fluid.③Ore-forming fluids of all sorts of mineral deposits in Limu orefield are all from the residual gas-rich fluids （magma—hydrothermal fluids）formed by two times of magmatic gas—liquid fractionation.③The magmatic—hydrothermal system consists of three branches which located in three different spaces,each of them interacts with different surrounding geological bodies by the way of hydrothermal alteration or crystallization, forming different types of deposits and vertical zoning.Conclusions:In the paper,we reconstruct the forming path of magmatic—hydrothermal system of rare metal granite and ore-forming process, and set up a new metallogenic model correlative.The results of the study would have enlightening significance for deep understanding magmatic evolution and diagenesis and mineralization of granite.