The Qulong giant porphyry CuMo deposit in the Gangdese metallogenic belt, southern Tibet, is characterized with a great amount of welldeveloped anhydrite. Detailed petrographic study discovered firstly that the Qulong deposit contains not only hydrothermal veinlike anhydrite but magmatic anhydrite. Our observation showed that magmatic anhydrite at granodiorite and biotite monzogranite stock formed at early stage of magmatic evolution occurs as inclusions in plagioclase and quartz. Accompanied with the occurrence of Srich apatite (0.11%~0.44% of SO2) and magnetite, magmatic anhydrite occurs as mineral inclusions in plagioclase phenocrysts hosted in monzogranite porphyry and granodiorite porphyry at the main mineralization period, with minor as phenocrysts. Late hydrothermal activity resulted in formation of a large amount of anhydrite+quartz+sulfide veins, constituting one of the dominating mineralization forms in this deposit. Electron microprobe analyses showed that the magmatic anhydrite is enriched in Sr (0.24%) compared with latephase hydrothermal anhydrite (Sr 0.03％), and this probably resulted from incompatible behavior of Sr or/and from advanced argillic alteration during the hydrothermal evolution of magma. The coexistence of magmatic anhydrite and sulfurrich apatite indicated that the magmas that formed the Qulong giant porphyry CuMo deposit is characterized with high S and high oxygen fugacity, providing an ideal case for studying the state and behavior of sulphur in the magma evolution of porphyrytype deposits.