The characteristics of the mineralized alteration of the W- Sn polymetallic deposits in South Hunan have been studied and summarized by detailed thin- section observation and electron probe microanalysies. The results show that all of the W- Sn polymetallic deposits have complex but similar mineral assemblages in ores and altered rocks, with ore minerals including cassiterite, chalcopyrite, wolframite (or scheelite), sphalerite, galena and altered minerals including fluorite, topaz, mica, K- feldspar, chlorite and spinel. Thus, the ore- forming fluids required for the formation of W- dominated and Sn- dominated deposits likely have similar sources and compositions. The mineral assemblages suggest that the ore- forming fluids are rich in volatiles of B and F, and contain mineralization elements of W, Sn, Cu, Nb and Be. We thus consider that the ore- forming fluids responsible for the Li- Be- Nb- Ta- W- Sn- Bi mineralization of different ore deposits in South Hunan sourced from the same granitic magma chamber, and propose a conceptual model.