Abstract: The Altun fracture zone is a gigantic sinistral strike-slip fracture zone in western China, It, 1600 km long and 100 km wide, extends in a NE direction. The fracture zone is composed mainly of the main Altun fracture and the Qiemo, Sanweishan, Lazhuglung-Kuyak, Janggalsay and Hongliugou-Lapeiquan fractures. From an analysis of its history of activity and geometric features, its activity belonged to the compressional-strike slip movement in the early stage of continental collision, while at present the strike-slip movement is dominant. This fracture zone and the Kunlun and North Qilian fracture zones combine to form the northern boundary of the Qinghai-Tibet plateau. It plays a role of connection and transform in the boundary.