Abstract: Large mammals are very sensitive to climatic and environmental changes, and the composition of a fauna depends on the ecology and environment. As a result, knowing how the population is structured is very important when trying to understand envimnmental characteristics by studying mammal fossils. First, we found the percentages of each age group, then estimated the causes of death in each population, and finally classify the habitat of these animals. The Hipparion fauna from the Linxia Basin is very similar in composition to assemblages from Baode, Shanxi and Fugu , Shaanxi, with rhinoceroses as the most abundant mammalian fossil (Deng, 2002) . 'Ibe genus Chilotherium from northern China was first recorded by Ringstlürn (1924) , and it was the richest during the Late Miocene in the Linxia Basin (Deng, 2001a) . It is valuable to recognize the age structure and habitat of the dominant Chilotherium wimani from the Upper Miocene in the Linxia Basin .