Based on the analysis of Landsat 7 Enhanced Thematic Mapper (ETM) images, geological mapping and study of the fault activity in the Beishan Region of Gansu province, this paper discusses the deformation mechanism of this region since the late Quaternary. The faults in this region can be classed into two groups in terms of their strikes: NE-striking and W-E-striking faults. All the NE-striking faults are normal faults with a left-slip component while all the W-E-striking faults are thrusts with a left-slip component. All the faults in this region are active in the late Quaternary. The present-day structure of the region indicates that it was formed under a NE-SW compression stress field. This stress field is caused by the collision between the Indian and Eurasian plates and the northward movement of the Indian plate. Under this stress field, the W-E-striking faults of the Paleozoic and Mesozoic were reactivated and the NE-striking faults were formed. Because the NE-striking faults are younger than the W-E-striking faults, the former offsets the latter. This phenomenon means that the collision between the Indian and Eurasian plates affects geological structures not only within the Qinghai-Tibetan Plateau, but also in region north to the plateau. Because the Indian plate is still moving northward at a speed of about 40 mm/a, we conclude that the tectonic deformation of the Beishan region will become greater in the future.