The Jiama superlarge copper-polymetallic deposit is located in the eastern part of the Gangdise metallogenic belt, and mainly includes four types of orebodies: skarn orebody, porphyry orebody, hornfels orebody and independent gold orebody. There are extensive magmatic biotites in the intermediate acid intrusions of the deposit, and hornblende is more common in some intrusions. On the basis of comprehensive geological survey in the mining area and detailed drilling core cataloging, the authors studied mineralogy and mineral chemistry of magmatic biotite in ore-bearing monzogranite porphyry and ore-bearing granodiorite porphyry as well as hornblende in ore-bearing granodiorite porphyry so as to reveal its petrogenic and metallogenic significance. The results show that the magmatic biotite in monzogranite porphyry and granodiorite porphyry is Mg-biotite, which is characterized by higher MgO, TiO₂, Al₂O₃, K₂O contents, and lower SiO₂, Na₂O content. Compared with granodiorite porphyry, magmatic biotite in monzonitic granite porphyry has lower content of TiO₂, FeO^T, MgO, MnO, Na₂O, BaO, and higher content of Al₂O₃, SiO₂. Hornblende in granodiorite porphyry belongs to actinolite, which is characterized by higher SiO₂, MgO and CaO content, and lower Al₂O₃, TiO₂, Na₂O and K₂O content. Biotite and hornblende thermometers show that the crystallization temperature of biotite in ore-bearing monzogranite porphyry is 740.1~783.8℃, with an average of 762.4℃, that of biotite in ore-bearing granodiorite porphyry is 750.3~766.9℃, with an average of 757.2℃, and that of hornblende in ore-bearing granodiorite porphyry is 654.1~698.9℃, with an average of 680.3℃. The mineral chemical characteristics of biotite and hornblende indicate that monzogranite porphyry and granodiorite porphyry are calc-alkaline series and I-type granite in the orogenic belt, which has the characteristics of crust-mantle mixed source. Monzogranite porphyry and granodiorite porphyry had higher oxygen fugacity (above NNO) and formed water-rich magmas, which was beneficial for the entry of copper, molybdenum and other ore-forming materials into ore-forming fluid.