Zircon UPb dating of the South Altun granites shows that, in the western segment of the South Altun, granite plutons at Yigan Village south of Qiemo County are aged 352±4, 349±2, and 343±3 Ma; while in the eastern segment of the South Altun, granite plutons north of Baiganhu Village are aged 447±4, 444±5, and 448±2 Ma, granites west of Mangya Town are aged 444±6 and 435±4 Ma, the granite from the Aketi Mountains is aged 265±2 Ma, Chaishuigou granite is aged 406±5 Ma, Changchungou quartz diorite is aged 469±3 Ma, and the granite north of Mangya Town is aged 462±8 Ma. Based on previous studies in conjunction with granite dating and geochemical study results in this paper, the South Altun granite can be divided into five episodes: episode 1, characterized by the granite association of quartz diorite+granodiorite+monzogranite, with affinities of Itype granite and an age of＞460 Ma; episode 2, characterized by the granite association of granodiorite+monzogranite+syenogranite, with geochemical affinities of Itype granite and an age of 435~450 Ma; episode 3, characterized by the granite association of quartz monzonite+syenogranite+alkali feldspar granite, with affinities of Atype granite and an age of 385~411 Ma; episode 4, characterized by the granite association of granodiorite+monzogranite with an age of 343~352 Ma, with geochemical affinities of Stype granite; and episode 5, characterized by the granite association of quartz diorite+monzogranite, with geochemical affinities of Itype granite and an age of 265 Ma. Based on the results of the above studies in conjunction with regional geological characteristics, it is considered that episode1 granitic magma activity might be related to the subduction of oceanic crust, episode2 magma activity might belong to postcollisional magma activity, episode3 magma activity might be related to the isostatic adjustment of orogen blocks after plate collision, episode4 magma activity might be related to Tethyan tectonic activity, and episode5 magma activity might be related to the Altun fault activity.