Eight molybdenite samples were selected from the Yaojiagou molybdenum deposit. The Re-Os isotopic model ages ranging from (166.1±2.3) Ma to (169.1±2.5)　Ma, yielded an isochron age of (168.8±3.9) Ma (MSWD=1.12) , which was interpreted to be the ore- forming age of the deposit. Combined with existing geochronologic data of Yaojiagou granit pluton, the authors assume that there were multistage of intrusions in Yaojiagou area and the Yaojiagou molybdenum deposit was related to the magma intrusion activities in （168.8±3.9） Ma.　In combination with metallogenic geological background, the authors infer that the Yaojiagou molybdenum deposit developed from Early to Middle Jurassic, influenced by magma and fluid function of post-collision between North China Craton and Siberia Craton.