Based on the seismic profile interpretation as well as ground survey and well data, the paper presented structural deformation features of the eastern sector of Altun fault. It extended NEE-wards from Akesai to northern Gansu, and did not terminate in the Jinta Basin or the Kuantaishan mountains to the northwest of Yumen city. Actually, it ended at the east of the Well Huatan 7 in the Huahai Basin, a Meso-Cenozoic basin located between the Kuantaishan mountains and the Jinta Basin. The structural deformation of the eastern sector of Altun fault occurred mainly in three periods: Late Oligocene, end of Pliocene and end of Late Pleistocene, with the later being most violent one. Spacially, the deformation became weakened from the west to the east. The deformational mode might be strike-slipping with thrusting, which gave rise to a group of thrusts which made up an arcuate fracture system disappeared SWW-wards, with a main tectonic style being a half-flower structure in profile.