One set of the arfvedsonite granitic porphyry dykes exposed widely in the Shichengzi area of Harlik Mountain, Xinjiang, NW China, was discovered. The dykes intrude into Late Paleozoic monzonitic granite plutons. The dykes are of porphyritic texture and massive structure. Phenocrysts consist dominantly of perthite and antiperthite, with matrix composed of albite, orthoclase, quartz, arfvedsonite and aegirine. The main elements analysis shows that arfvedsonite granitic porphyry has high contents of SiO2 and Na2O+K2O, and low contents of Al2O3, MgO and CaO. These samples have a high ∑REE value and distinct fractionation between LREE and HREE, especially enrichment in LREE. The chondritenormalized REE patterns show obvious rightleaning pattern with strong Eu negative anomaly. In addition, the primitive mantlenormalized trace elements pattern shows show high 104 Ga/Al, Zr and (Zr+Nb+Ce+Y) values, and the depletion of Ba, Sr, P, and Ti and enrichment of Th, U, Zr, and Hf. The petrographic and geochemical data above indicate that the arfvedsonite granitic porphyry dykes are Atype granite. Positive εNd(t) (4.13~4.75) values and young Nd model ages (tDM2) indicate that arfvedsonite granitic porphyry was derived from juvenile crust. LAICPMS zircon UPb dating suggests that the dykes emplaced at Late Permian (2597±45 Ma). The ages of two old zircons in country rocks concentrate around two peaks (2168 to 2635Ma and 1677 to 1973Ma), respectively, which indicate the existence of Precambrian basement in Harlik Mountain, but was reformed by juvenile crust. Combined with regional geologic background, the Harlik Mountain area was in tectonic setting of postcollision during Carboniferous and early Permian and then entered the intracontinental extension during Late Permian.