The study of garnet pyroxenite reveals that the ultramafic block in Raobazhai within the Dabie Mountains is of metamorphic origin rather than a slice of primitive mantle. It underwent an evolutional process from spinal_Al_rich pyroxene facies (750℃, 1.1 GPa) through spinalgarnet facies (850℃, 1.5 GPa) to granulite facies (800℃, 0.85 GPa). The metamorphic history of the block is obviously different from that of ultrahigh_pressure complex in the southern Dabie Mountains. It may represent the upper rock of subducting continental crust of the south- ern Dabie Mountains characterized by a high geothermal gradient. The relationships of the granulitization of Raobazhai and other ultramafic blocks to regional granulite facies metamorphism suggests that the Dabie basement has been thoroughly reformed, and the high_grade metamorphism of the northern Dabie Mountains in Anhui Province is only a mirror of the postIndosinian granulite facies event.