The ultra-high pressure metamorphic belt in the southern part of the Dabie Mountains is mainly distributed in the subducted basement of the Yangtze plate (the Dabie Group) and composed of eclogite with small amounts of ultramafic and jadeite-quartzite blocks and their country rocks. Their mineral assemblages, especially the inclusions of coesites and diamonds suggest that these rocks underwent an ultra-high pressure eclogite facies metamorphism. The chemical corn-positions and REE contents of the eclogites and the characteristics of the rock association including garnet-peridotite, and jadeite-quartzite indicate that the belt is a tectonic melange one composed many of continental crustal rocks mixed with some mentle-derived and oceanic crustal rocks. The formation of the ultra-high pressure metamorphic belt is related to the collision between the Sino-Korean and Yangtze plates during the early Mesozoic, and was the product of northward subduction of the continental crust of the Yangtze plate to a depth greater than 90 km. The ultra-high pressure metamorphic belt was uplifted rapidly by obduction to the middle crust in the process of continuous subduction-obduction in the collisional tectonic setting, so it was an allochthon thrust on the subducted basement of the Yangtze plate.