Abstract: The Xin'an molybdenum deposit, located in the middle of Wuyi Mountain's western slope, is a newly discovered porphyry Mo deposit. The geological characteristics of the deposit is presented in this paper. The Re-Os model ages of the molybdenites are between (166.7±2.3) Ma and (169.5±2.4) Ma, with a calculated isochronic age of (168.3±1.7) Ma indicating that molybdenum mineralization occurred in the early Yanshanian period, belonging to the Mesozoic first large-scale mineralization. The age of this deposit indicates that a dependent Mo mineralization may have existed in this area before large-scale tungsten/tin mineralization. According to collected molybdenite Re-Os dating results, molybdenum mineralization times are mainly concentrated in Yanshanian which includes three stages of 130-140 Ma, 150-160 Ma and 165-170 Ma, meaning molybdenum mineralization is a long-term evolutionary process. This result is not only important for studying the regional magmatic activity and mineralization, but it can also guide further exploration work.