A fairly complete medium-pressure Barrovian type progressive regional metamorphic belt can be recognized in the Caohe Group, which includes chlorite, Liotite, almandine, staurolite, kyanite and sillimanite zones. The regional metamorphism of the Caohe Group shows a series of special characteristics in such aspects as mineral ass0mblages, rock types, chemical and physical properties of minerals, which are consistent with the features of various metamorphic zones of the region. During the regional metamorphism, the A1z03, Fe0+Fez03 and Mg0 contents of almandine increased but the Ca0 and Mn0 contents decreased with the heigh- tening of the grade of metamorphism. Using the garnet-biotite mineral pair as a geothermometer, the author has determined the formation temperatures of the metamorphosed argillaceous rocks:the almandine zone is below 450℃, the staurolite-kyanite zone 450-600℃, and the sillimanite zone 600-620℃.