The garnet-sillimanite-cordierite gneiss, which has been identified from the Chahanhe Group in the northern region of the Oulongbuluke block, consists of garnet, sillimanite, cordierite, biotite, plagioclase, ilmenite, and a small amount of K-feldspar. Petrographic observation shows that three stages (M1, M2 and M3) of mineral assemblage can be recognized. They are M1:Pl±Kfs+Grt+Sill+Qz, M2:Pl±Kfs+Grt+Sill+Qz+Ilm+Bt, and M3:Crd+Bt+Ilm+Qz+Grt+Pl±Kfs. Phase equilibrium modelling shows that the peak p-T conditions of the garnet-sillimanite-cordierite rock are p=0.92~1.08 GPa and t>790℃, and experienced a heating decompression during exhumation. The metamorphic ages acquired from zircon and monazite U-Pb dating by LA-ICP-MS are 1 133 ±14 Ma and 1 125 ±37 Ma, respectively, which represent the timing of granulite-facies metamorphism. Combining regional geology with our data, we suggested that the garnet-sillimanite-cordierite rock in the Chahanhe Group formed in an arc or back-arc system related to oceanic subduction. The magmatic-metamorphic complex belt in the northern region of the Oulongbuluke block underwent an evolutionary process from subduction-accretion to collision orogeny during late Mesoproterozoic to early Neoproterzoic, which is a response to the convergence process of Rodinia supercontinent.