Molybdenite occurring widely in metal deposits has been considered to be the most ideal target for directly dating deposits due to its high content of Re and Os and low content of common Os. However, it is very difficult to collect enough pure molybdenite grains for dating in many types of ore deposits due to its fine-grained mode of occurrence and low content. As we know, the Re and Os are chalcophile and siderophile elements, and they would be concentrated mainly in sulfide minerals rather than in silicate mineral crystals. So it is theoretically feasible to determine Re-Os age directly by using molybdenite-bearing whole rock samples. To examine this idea, the authors chose age well-constrained Dexing porphyry copper orefield as a case study. In the study, five molybdenite-bearing rock samples were collected from drill holes in the Zhushahong deposit for Re-Os isotopic analysis. As a result, the five samples yielded a high-quality isochron age of 172.6 ±2.6 Ma, which is the same with previously reported Re-Os age of the deposit obtained by using pure molybdenite samples. This shows that directly dating molybdenite-bearing wholerock samples is not only feasible but also reliable. Additionally, the Re-Os age of molybdenite the authors reported in the study is in accordance with the zircon U-Pb age of ore-forming granodiorite porphyry, implying that the mineralization and the porphyry intrusion are genetically related to each other. The previous Rb-Sr ages and K-Ar ages of the deposit do not coincide with the Re-Os age and the U-Pb ages, which might be caused by the late hydrothermal alteration and thermal events that damaged or reset the Rb-Sr and K-Ar isotopic systems.