Abstract：Beishan area is an important metallogenic belt, and the Baishantang Cu polymetallic deposit is one of the representative porphyry copper deposits. Two kinds of magmatic rocks along ore belt I in the Baishantang ore district were dated by the zircon LA-ICP-MS U-Pb method, which yielded a porphyry granite diagenetic age of （275.0±3.0）Ma (MSWD =1.17) , indicating early Permian. Two groups of ages were obtained for rhyolite porphyry: a magma zircon group of the rhyolite porphyry has an age of （371.1±2.8）Ma (MSWD=1.7) , suggesting late Devonian. The other inheritance zircon group of inheritance zircon with remarkable rounded shape or enveloped in the former group has ages of （2627±35）Ma, （2598±35）Ma, （705±44）Ma, （1722±48）Ma, （1642±51）Ma, （1213±54）Ma, which can be assigned roughly to 2.6 billion years, 1.7 billion years and 1.2 billion years, indicating that the rhyolite porphyry was related to the remelting of the upper-middle crust in late Devonian, as also shown by the geochemical characteristics.