The distribution of elements between melts and coexisting aqueous fluids plays an important role in magmatic hydrothermal oreforming process. Tin ore is one of the representatives related to granitic magma evolvements. Cognition of tin species in granitic silicate melts, fluids and the partition coefficients is a key to recognition of the mechanism of tin ore-forming. The distribution of tin between granitic silicate melts and fluids is not only influenced by temperature, pressure, oxygen fugacity, but also controlled by NBO/T、Alkali and Alkali/Aluminium of melts and the content of fluids. Tin geochemical characteristics in melts and fluids are influnced significantly by different contents of volatiles fluorine and chlorine. 