Abstract: The granitic plutons in the eastern section of Nanshan within Qinghai Province consist of monzogranite, granodiorite and tonalite. The zircon U-Pb dating results of monzogranite and granodiorite are 241±3Ma, 245±3Ma and 249±3Ma respectively, representing the crystallization age of those granitoids. In tectonic discrimination diagram for granitic rocks, these samples fall in the subduction field, indicating the north subduction of the Zongwulong oceanic crust in Early Triassic. Through the research on petrogenesis, ages and tectonic setting for granitic plutons in the eastern section of Nanshan within Qinghai Province along Zongwulong belt, this paper provides important evidence for the tectonic environment and geodynamic mechanism of the Zongwulong belt in Early Triassic.