Garnet-mica schist from the Shizui Subgroup of Wutai Group is chiefly composed of garnet, biotite, muscovite, plagioclase, quartz and ilmenite, with a few samples containing epidote, staurolite, kyanite and ortho-amphibole. Samples have SiO₂ 51.75%～69.06% and Al₂O₃ 11.99%～20.39% with a few samples being poor in sodium. Samples exhibit higher LREE and lower HREE in REE patterns without obvious Eu anomaly, and their high strength element compositions and large ion lithophile element compositions are similar to those of classical shales in the world. Correlations between related elements imply that clay minerals dominate the rock bulk compositions. Based on a series of diagrams such as geochemical classification, heavy mineral accumulation, source rock and tectonic setting discrimination, the authors found that the protolith of the rocks was shales without obvious heavy mineral accumulation. The sediments mainly came from those coeval TTG rocks and/or basic rocks in Wutai area, and were deposited in an arc basin environment at about 2.53～2.50 Ga. Combined with the results of metamorphic equilibria modeling using THERMOCALC method and metamorphic zircon dating using SHRIMP method, the authors have found that the garnet-mica schist experienced a kyanite-type metamorphism with a clockwise p-t path at ～1.95 Ga.