Abstract: The petrochemical and geochemical features of Early Permian basic volcanic rocks in the Mingteke area on the north slope of the Karakorum Mountains indicate that the rocks are back arc basin volcanic rocks with both the nature of spreading ocean ridge basalt on the sialic basement and the characters of calc alkaline island arc tholeiite.The formation of this back arc basin was related to the spreading and northward subduction of the Paleo Tethys oceanic basin along the line from the Xijir Ulan Lake Kongke Mountain Pass to Mount Qogir,which gave rise to the Late Paleozoic active continental margin of the southern Tarim plate.