LA-ICP-MS U-Pb zircon dating on the plagiogranite and biotite plagiogranite from the Wutubulake iron deposit district, southern margin of Altay, Xinjiang, yielded concordant ages of 385.6~2.3 Ma(MSDW=0.13) and 387.7~2.1 Ma(MSDW=0.23),indicates that the two comagmatic plutons were formed at the beginning of the Middle Devonian. The Wutubulake iron deposit is closely related to the magmatic intrusion, writers hereby confine the iron deposit formed at the beginning of the Middle Devonian appreciably later than 388～386 Ma. The Wutubulake plagiogranite and biotite plagiogranite are characterized by enrichment of silica(SiO2=66.01%～79.14%) and Na(Na2O＞K2O). The A/CNK{A/CNK=n(Al2O3)/[n(CaO)+n(Na2O)+n(K2O)]} ratios are less than 1.1,indicates that both of them are weakly peraluminous. Geochemically, the Wutubulake granites are enriched in Th, Ta, Hf, but depleted in Rb, Ba, K, Sr, P. The REE patterns are characterized by enrichment of LREE[(La/Yb)N=2.46～7.24], with moderately or significantly Eu negative anomalies.In combination with previous studies, writers concluded that the Wutubulake plutons were formed in continental arc at active extensional continental margin setting related to the subduction of plate.