The Baoyintu Group in the central western Inner Mongolia, mainly consists of mica schist, amphibolite, quartzite and marble. Typical progressive metamorphism is developed in the mica schist, which, however, is still poorly studied. In this paper, the mica schist in the Baoyintu Group has been systematically studied in terms of petrography, mineral chemistry P- T paths and zircon U- Pb geochronology. Petrographic study on three mica schist samples shows different peak mineral assemblages, respectively of garnet+muscovite+biotite+plagioclase+quartz in sample LS89, staurolite+muscovite+biotite+plagioclase+ilmenite+quartz in sample LS93, garnet+kyanite+muscovite+biotite+plagioclase+ilmenite+quartz in sample LS07. In addition, the late superposition〖JP〗 of andalusite is observed in samples LS93 and LS07. Phase equilibrium modeling defines a progressively trending peak P- T condition for the three mica schist samples, such as 577℃, 0.73 GPa in LS89, 620℃, 0.78 GPa in LS93 and 670℃, 0.8 GPa in LS07. Moreover, the peak P- T conditions of the samples yield geothermal gradient of 18~20 ℃/km, being typical medium P/T series. The P- T paths of the samples show clockwise evolution including an early prograde stage until the peak stage, followed by cooling and decompression, representing a crustal thickening setting. Zircons in mica schist of the Baoyintu Group typically have metamorphic rims with Th/U ratios of 0.004~0.02, and the LA- ICP- MS U- Pb dating of the zircon rims yield a weighted mean of 398±6 Ma, which is interpreted to represent the age of near- peak metamorphic stage. Consequently, we interpreted that the Barrovian- type metamorphic zone of the Baoyintu Group may have formed in a collision orogenic background related to the closure of the Paleo- Asian Ocean.