In recent years, the differential Interferometric Synthetic Aperture Radar (D-InSAR) technique has been widely used in monitoring deformation on the Earth's surface. Compared with conventional approaches (such as global positioning system (GPS) monitoring), application of the D-InSAR technique has many advantages in surface deformation monitoring. In this paper, the D-InSAR technique is applied to study the crustal deformation characteristics of the eastern segment of the Altyn Tagh Fault (ATF), which is an important boundary of crustal deformation in the north-eastern area of the Tibetan Plateau. To the north of the boundary, the deformation gradually decreases from 2.8 cm in the west to 0.8 cm in the east; to the south of the boundary, the deformation presents different characteristics at the two sides of the western part of the North Qilian Shan Fault (NQF). At the south-west side, the deformation is intense, with relatively weaker deformation of 1.6∼2.1 cm inside the Changma Basin and stronger deformation of 2.2∼6.0 cm outside the Changma Basin. At the north-east side, the deformation is smaller than that in the other side, with a decrease from 1.3 cm in the west to nearly 0 cm in the east. North-east to the western part of the NQF, there exists negative deformation. This is because when the northern margin of the Tibetan Plateau was moving to the north-east, it was blocked off by the rigid Alashan Block and was bent down close to the north-east of the Qilian Shan Orogen to form a foreland basin. This paper also shows that currently the ATF is active and has left-lateral strike-slip. The slip rate of the eastern segment of the ATF is 4.7 mm/year. For different locations, the slip rate is different.