A continental sedimentary sequence of large thickness from Oligocene to Pleistocene is well developed in the Kumkal basin, Xinjiang, which recorded the process and scale of the uplift of the west part of the Qinghai-Tibetan Plateau. The main leveling plane was formed after the Miocene but before the Pliocene, a period featuring a change of biotic association from species like the ones in the present mountainous regions of South China to those suitable to salt-water environment. Geological data indicate that the scale of the uplift was fairly large and the horizontal movement was very strong in the western plateau. The features of mammal fossils in combination with the elevation of fossil beds and the characters of river erosion geomorphic features disclose that the uplift scale in this area is no more than 500 m since the late Pleistocene.