The Well ZY1 in the eastern Xuanhua area of northwestern Hebei Province revealed that there were four layers of rhyolite porphyry intercalated in the shale of the Mesoproterozoic Xiamaling Formation.The LA-ICPMS zircon U-Pb age of 226.5±1.9 Ma is dated in this paper,indicating that the rhyolite porphyry intruded in the middle Late Triassic.The rhyolite porphyry in this area does not contain alkaline femic minerals,so it should not belong to alkaline rock.The middle Late Triassic rhyolitic porphyry discovered in this area enriches non-alkaline rocks and their dating data in the northern margin of the North China Craton (NCC),where the tectonic regime in Middle—Late Triassic is transformed from post collisional/post-orogenic extension to intraplate extension.This study has important theoretical significance for analysis of the Indosinan active history of thr NCC,and has practical significance to search for mineral resources.