According to data of fluid inclusions within minerals and thermochemical estimation of dehydration reaction during granulite-facies metamorphism of Jining Group and Qianxi Group, the fluids existent at the peak stage must have been carbonic, withx(CO2+CH4)≈70%~80% andx(H2O)≈10%~20%, the density is generally 1.0~1.1 g/cm3. In the Jining Group, components of the metamorphic fluids and activity of H2O seem to have been spatially inhomogeneous, and were apparently controlled by lithology. TheαH2Ovalues of Al_rich gneisses, biotite hypersthene gneisses and basic granulites are 0.1~0.2, 0.2~0.4 and 0.4~0.6 respectively. Such inhomogeneity indicates that the fluids might have experienced internal buffering, and did not permeate pervasively through rocks. They were probably developed as a result of various kinds of devolatilization and oxidation of the organic materials (now as crystalline graphite) extensively distributed in rocks, both of which must have occurred at the progressive metamorphic stage. Moreover, H2O could escape from the system more easily than CO2, and this might be partly related to their carbonic affinity. On the contrary, the components and physical habits of fluids during metamorphic peak of the Qianxi Group were rather homogeneous in space, being independent to lithology. In Taipingzhai district, for example, theαH 2Ovalues of rocks of all the three types are 0.13~0.25 with XH2O≈0.1~0.2. These features suggest that the fluids in this region were probably of external_buffering, and had pervasively permeated through rocks. CO2in fluids might mostly have come from underplating mantle_source mafic magma and its crystallization process.