Exposed in the middle segment of the Palaeoproterozoic Trans-North China Orogen, the Yixingzhai pluton on the southern slope of the Hengshan Mountain and the Chechang-Beitai pluton on the northern slope of the Wutai Mountain experienced amphibolite facies metamorphism and were cut by metamorphosed diabase dykes. The Yixingzhai pluton consists of transitional granodioritic gneiss, quartz dioritic gneiss and dioritic gneiss. Its metamorphic peak p-T conditions are estimated to be of 710~760℃/0.65~0.75 GPa and the retrograde metamorphism occurred at 560~690℃/~0.46 GPa. The metamorphic peak is ascribed to typical middle p-T facies series. K-Ar dating of metamorphic hornblende suggests that the metamorphic peak occurred at about 1.84~1.82 Ga. The Chechang-Beitai pluton consists of biotite-muscovite granitic gneiss and the metamorphic peak p-T conditions are estimated to be of 550~690℃/0.92~1.14 GPa, belonging to the top middle p/T facies seies. K-Ar dating of metamorphic biotite implies that the metamorphic peak occurred at about 1.80 Ga. Geochronologic research indicates that these two plutons were involved in the late Palaeoproterozoic orogenic event of Trans-North China Orogen deciphered at about 1.96~1.80 Ga.