Wula Mountains—Daqing Mountains, the important gold mineralization belts in the northern margin of the North China Block, host the large Hadamegou—Liubagou gold—molybdenum orefield, but oreforming time and tectonic settings of the orefield are still in dispute and the orefield has long been considered the products of tectonic activity during the Mesozoic. Quartz veintype and potassic alterationtype molybdenum mineralization paragenetic with gold was recently discovered at the depth of the Hadamengou gold deposit. ReOs isotopic method in this study was employed to chronologically determine molybdenite paragenetic with Aubearing pyrite. Four samples of molybdenite yielded an isochrone age of 386.6±6.1 Ma (MSWD=1.18), with a weighted average of 386.4±2.7 Ma（MSWD=0.55）and an initial 187Os value of -0.02±0.41. Combined with other geological evidence, our result suggests that the gold mineralization event at the Hadamengou area could date back to the Early Devonian, which indicates an event of tectonomagmatic activity occurring in the early Hercynian period. The data acquired above are of important significance, both theortically and practically, in further understanding the gold mineralization and regional geological evolution of this area.