The authors reviewed the characteristics of ore forming fluids of quartz-vein tungsten deposits associated with S type granites and porphyry copper deposits associated with I-type (some associated with A-type) granitic rocks. The two fluid systems are similar in that both of them are derived from magmatic evolution, with involvement of meteoric water in the late stage. On the other hand, they are different in the following aspects: 1) the ore forming fluids of quartz-vein tungsten deposits belong to the H2O-NaCl±CO2 system; 2) boiling and phase-separation are common in porphyry copper deposits and may have played important roles for the transport and deposition of Cu; 3) and W is more associated with O and Na in fluid systems while Cu is with Cl and S, so the formation and the type of deposits depend in part on availability of these elements in the fluids.