Abstract: Qitianling A-type granite has a close temporal, spatial and genetic relationship with Furong superlarge tin deposit.Based on the studies of fluid inclusion geochemistry, three types of fluid inclusions in quartz crystals from Qitianling A-type granite, namely, melt inclusions, fluid-melt inclusions and fluid inclusions were indentified. Data from the analyses of these fluid inclusions indicate that the magmatic fluid can be derived from the Qitianling biotite granite during magma differentiation. This fluid is similar to the high salinity ore-forming fluid of the Furong superlarge tin deposit with the high temperature and H2OCl rich characteristics and with salinity around 13%~50% NaCl equiv. From all the above evidences, we can conclude that the high salinity ore-forming fluid was dominantly of magmatic origin which was extracted from the Qitianling biotite granite during magma differentiation.