In this paper, we present new petrological, geochemical and LAMCICPMS data for metasedimentary rocks from the Baijingsi area, North Qilian Mountains, in which typical earlyPaleozoic ophiolitic sequences and HP/LT metamorphic rocks have been previously recognized. The studied metasedimentary rocks contain eclogitic facies assemblages reflecting PT conditions of 450~520℃ and 1.9~2.3 GPa, consistent with those of adjacent eclogites. Geochemical data indicate that the precursor rocks of the metasedimentary rocks were immature sediments formed in continental margin or island arc environments. UPb dating of detrital zircons from metasedimentary rocks is concentrated around 1800 Ma and 540~600 Ma, along with zircon Hf isotopic characteristic, suggesting that they derived from both the mixture of Paleoproterozoic metamorphic basement and Late Neoproterozoicearly Paleozoic oceanic materials, which were probably accreted into active continental margin during subduction. These data imply that tectonic erosion of the active continental margin of North Qilian occurred during the Mesozoic ocean and crustal subduction, resulting in the formation of hangingwall sediments in the upper plate (forearc basin or accretionary prism), which were then transported into the subduction zone to a depth of 60~70 km and exhumed after eclogitefacies metamorphism.