In order to get further understanding about the magmatism and its relationship with mineralization, the geochemical characteristics and zircon U-Pb age of quartz-monzonite porphyry in Anji polymetallic ore district in western Zhejiang have been studied. Considering that quartz-monzonite porphyry exists along Huzhou-Xuechuan fault and is cut off by Xiaofeng-Sanmenwan fault, this age indicates that Huzhou-Xuechuan fault was activated in Early Cretaceous and also constrains the earliest time when Xiaofeng-Sanmenwan fault activated. The magmatism formed in the same time with mineralization, and mineralization also has a close relationship with the complex body in space, so it is believed that the mineralization is related to the magmatism in this study area.