Abstract: The Altun Tagh fault, a famous huge sinistral strike-slip fault in NW China, is composed mainly of the Altun master shear and several secondary fracture. The relationship between master and secondary structures may he explained by a simple shear model. It is one of the typical strike-slip pull-apart basins which formed in the setting of releasing splay area in Altun Tagh. The Xorkol basin began to extend in Pliocene and its extensional width is now about 40km. The extending rate of the Xorkol basin is about 0.8cm/a. Based on the same rate, the displacement of the Altun master shear is estimated 320km from later Eocene.