Abstract: Xifengsi of Lu’an is located in the Dabie orogenic belt, and the major type of intrusions is syenite, which can be further divided into aplitic syenite, porphyaceous syenite, macrocrystalline syenite and syenite porphyry, with Mo mineralization closely related to the intrusion of syenite porphyry. The authors carried out the study of geochronology about major intrusions in the Xifengsi ore district. The U-Pb ages of zircon show that, from the old to the young, there are porphyaceous syenite, aplitic syenite, syenite porphyry and macrocrystalline syenite, all formed in Early Cretaceous period. Combined with the study and the regional correlation, the authors hold that the Xifengsi Mo mineralization district has has similar background and ages to large molybdenum deposits like Shapinggou and Qian’echong and thus possesses a good potential of molybdenum mineralization.