The Aketishan granite is located in the southern margin of the Altun fault zone, but its formation age differs greatly from other rocks in the area and its strike is obviously controlled by the branch fractures of the Altun fault zone. Zircon LA- ICP- MS U- Pb dating of granites from Aketishan yielded a crystallization age of about 262 Ma. Its formation may be related to the large- scale linear tectonic movement in the south Altun area during the variscy- indosinian period. The granite consists mainly of quartz diorite and granodiorite, with dark minerals being mainly hornblende and biotite. The geochemical characteristics show that an average A/CNK value of <1. 1, indicating that the granite belongs to the typical high- K calc- alkaline series with quasi- aluminous to weakly peraluminous. Large ion lithphile elements (Rb, Th and K) are relatively enriched and high field strength elements (Nb, Ta, P, Sr, Ti) are in distinct negative anomaly. The REE distribution patterns show medium negative Eu anomaly, with the mean δEu value of 0. 73 and the mean (La/Yb)N value of 14.57. The trace discrimination diagram shows that the granite samples fall into the I- type granite area (VAG). The zircons Lu- Hf isotope analysis indicates that the εHf (t) values of the granites are all positive and the average peak value of two- stage Hf model ages is 943 Ma, suggesting that the source rocks are partial melting of Neoproterozoic juvenile crustal materials. The strike- slip movement of the Altun fault started from the ductile deformation of the deep crust during the Indosinian period, subsequently followed by brittle fracturing in the shallow surface, thus forming a large- scale strike- slip fault zone. The formation of Aketishan granite was related to decompression melting of deep crust.