The volatile- rich hydrosilicate melts generated by magma liquid immiscibility represent important forms of ore- forming liquids for W- Sn polymetallic deposits associated with the highly- fractionated granite. Two types of volatile- rich hydrosilicate melts have been identified in the W- Sn polymetallic deposits of South Hunan. The first type is Na- and volatile- rich and represented by the albite- tourmaline- quartz pockets hosted in altered alkali- feldspar granite. The second type is K- and volatile- rich and represented by the lithian muscovite- fluorite pockets or blocks hosted in altered and mineralized granite porphyry. These two types of melts can be found in the same ore deposit, show negative compositional relationship between K2O and Na2O, and develop melt- fluid inclusions. They have close spatiotemporal and genetic relationship and represent different products of magma liquid immiscibility. In South Hunan, the K- and volatile- rich melt is probably responsible for the greisen- type, the structure- altered zone- type and the K- feldpar- granite- type W- Sn polymetallic mineralization, while the Na- and volatile- rich melt is linked to the albite- granite- type Nb- Ta mineralization.