Detailed geological mapping reveals that metamorphic rocks outcropped in Qingshuigou-Xiangzigou area of the North Qilian Mountains mainly consist of eclogite, blueschist, phengite-quartz schist, metachert, marble and serpentinite. Geochemical data show that the protolith of eclogite was composed of MORB or OIB. Two types of blueschists were identified: the protolith of type Ⅰ was basic volcanic rock, that of type Ⅱ was sedimentary rock derived from ocean island arc and/or continental arc; phengite-quartz schist was derived from terrigenous clastic rocks formed at continental margin. Protolith of metachert was hydrothermal chert deposited far away from the continental margin. Marble came from limestone. The SHRIMP Ⅱ zircon U-Pb dating results show the protolith of eclogite and that of type Ⅰ blueschist are 500±4 Ma and 529±5 Ma, respectively. Zircon Lu-Hf isotopic values indicate that the protolith of eclogites has been heavily influenced by ancient crust, and the protolith of type Ⅰ blueschist was derived from depleted mantle. Combined with the previous data, the authors hold that the protolith of metamorphic rocks in the high-pressure and low-temperature metamorphic belt shows heterogeneous features, i.e., with different protolith natures and various protolith ages. These data suggest that the rocks with different protolith natures and various ages were carried into the great depth of the subduction zone during the northward subduction of paleo-Qilian Ocean in early Paleozoic, and formed mélange under the high-pressure/low-temperature condition, thus representing an early Paleozoic subduction channel related to oceanic subduction.