The Waxing Mo polymetallic deposit is a newly discovered porphyry type deposit in the Lesser Xing'an Range-Zhangguangcailing metallogenic belt. There are several periods of magmatic activity in the mine area. Zircon U-Pb dating results show that the emplacement ages of monzonite granite, granodiorite and biotite monzonite are 177±1.9 Ma~174±1.2 Ma, 170±1.9 Ma~169±2.1 Ma, and 172±1.5 Ma~172±1.4 Ma, respectively. The three types of granites are all characterized by high SiO₂ (64.41%~77.77%) contents, and are enriched in large ion lithophile elements, depleted P₂O₅ (0.02%~0.21%) and high field strength elements such as Nb and Ta. The A/CNK values are between 0.99 and 1.21], suggesting they belong to high-K calc-alkaline metaluminous-slight peraluminous type I granite. The whole rock Nb/Ta ratio (7~13) is comparable to that of the crust. Zircon εHf(t) values range from 3.9 to 18.8, indicative of juvenile crustal origin. A number of mafic microgranular enclaves (MMEs) are observed in these granitoids, suggesting that mantle-drived magma was involved in the source region. Combined with the regional tectonic evolution history, we believe that the granite in the Waxing ore field was formed in the late collision-post-collisional setting. We found that granodiorite and biotite monzonitic granite have good spatial relationship with Cu-W and Mo-W mineralization, respectively, and their emplacement ages are correlated with the weighted average age of molybdenite Re-Os (169.0±2.2 Ma; MSWD=0.042). These support the granodiorite and biotite monzonitic granite are syn-mineral intrusion, while the monzonite is pre-mineral pluton. Combined with zircon U-Pb chronology and Hf isotope characteristics, the biotite monzonite granite and granodiorite may be the products of different magmatic evolution degrees at the same time, and higher evolution degrees may be conducive to Mo enrichment in magmas. Ratios of granite (La/Yb)_N decrease abruptly from pre-mineral to syn-mineral intrusions, probably indicating a transition from compression to extension, which may be conducive to Mo formation.