The Wushan skarn copper deposit is genetically associated with the Wushan granodiorite. Here, we investigate the petrography and mineralogy, and determine the formation conditions of biotites within the Wushan granodiorite, and discuss the significance of these minerals in terms of petrogenesis and mineralization. Electron microprobe analysis indicates that biotites within the granodiorite are Magnesio-biotites that contain relatively high Mg and Ti concentrations, with low Fe and Al. The ionic coefficient of AlVI varies from 0.03 to 0.19, with ¿FeO/(¿FeO + MgO) ratios of 0.531¿0.567, and MgO concentrations of 12.80¿14.06 wt%, indicating that the Wushan granodiorite is an I-type granite. The biotites crystallized at temperatures (T) of 720°C¿750°C, under oxygen fugacity (fO2) conditions of ¿11.6 to ¿12.5 and pressures (P) of 0.86¿1.03 kb, indicative of a crystallization depth (H) of 2.84¿3.39 km. These data indicate that the Wushan granodiorite formed under conditions of high temperature and high oxygen fugacity, suggesting in turn that it is prospective for magma-hydrothermal mineralization and is likely to have contributed to the formation of the Wushan skarn copper deposit.