The Late Cenozoic deposits of the Linxia Basin in Gansu Province are relatively thick, bearing abundant mammalian fossils of different periods from the Late Oligocene to the Early Pleistocene. These fossils are important materials to study the evolution of mammalian faunas and their relationship with climatic and environmental backgrounds. The diversity variations of mammals in the Linxia Basin were very noticeable throughout the Late Cenozoic, which are divided into different stages: the Middle Miocene, Late Miocene and Early Pleistocene have the highest diversities, the Late Oligocene and Early Miocene have the lowest, and the Pliocene has the moderate. The climatic and environmental variations of the Linxia Basin in different ages, which are judged from mammalian diversities, are highly consistent with other independent evidence, and closely relevant to the uplift of the Tibetan Plateau.