This paper deals with late Quaternary extension occurred along the eastern marginal zone of the Xizang (Tibetan) Plateau, based on Landsat TM imagery interpretation, field observations and optically stimulated luminescence (OSL) dating. The results show that late Quaternary extension has been observed along the longitudinal Anninghe valley, along the Daliangshan structural zone, in the Zoige basin and in the upstream Minjiang river. The characteristic feature of these extensional structures is the elongate valley controlled by normal faults and filled with late Quaternary deposits. According to the stratigraphic ages and OSL dating results, normal faulting occurred mostly in Middle Pleistocene, beginning from latest Early Pleistocene (1.2~0.9 Ma), and ending in earliest Late Pleistocene (100~200 ka). Since the Late Pleistocene, the tectonic regime has changed to strikeslip and reverse faulting one. The occurrence of the Middle Pleistocene extension along the eastern margin of the Tibetan Plateau may be the response to postorogenic collapse of this marginal zone.