The Late Paleozoic meta_basalts and gabbros exposed in Kuerti area of north Xinjiang are characterized by LREE depletion of different degrees and Nb, Ta negative anomalies, suggesting that they contain both MORB_like and arc-like components. The compositional characters of these meta_basalts and gabbros are much similar to those of the typical back-arc basin basalts (BABB) (e.g., Mariana and Okinawa BABBs). Therefore, they are presently determined to be of Kuerti BAB-ophiolite, most probably representing a crust part of the intraocean back-arc basin produced by subduction of the Paleoasia ocean. Recognition of the Kuerti BAB_ophiolite implies that the north Xinjiang area was an ancient subduction zone in early Late Paleozoic. A Paleoasia Ocean separated Siberian plate from Kazakhstan-Junggar continental plate at that time. The collision between the two continental plates and the subsequent orogeny in this area most likely took place after the disappearance of Paleoasia ocean in Carboniferous-Permian period.