Located in the southwestern section of the Fujian, the Shierpai ore deposit in Wuping county is a newly discovered molybdenum deposit. Molybdenum mineralization occurs within the biotite granite stock or along its contact zone with Neoproterozoic and Late Paleozoic metamorphic rocks. Ore bodies consist of veins, veinlets and disseminated blocks. Re Os dating of five molybdenite samples collected from the main ore body shows that the isochron age is (151±2) Ma and the model ages range from 149.7 Ma to152.8 Ma with an average value of (150.8±1.3) Ma, a little later than the age of the ore bearing wall rock, the biotite granite. It can thus be considered that the biotite granite and the molybdenum deposit were both formed in Late Jurassic, and that magmatism and mineralization took place in early Yanshanian period in the Southwestern Fujian depression. Combined with other isotopic age data from the molybdenum deposits in adjacent areas, it can be inferred that the large scale molybdenum mineralization in the southwestern Fujian depression occurring during the early Yanshanian. Magmatic activity induced by Indosinian transition from sustained platform to active continental margin accompanied by compressing and uplifting in early Yanshanian(about 160~145Ma) and later Yanshanian tectonic reworking with the conversion from compressing to pulling(about 105~90 Ma) ,seems to have been the dominant factor responsible for the formation of the molybdenum deposit.