280 species and subspecies were documented on mammal biodiversity in the Yangtze River Basin. They belong to 11 orders, 36 families and 135 genera, of which, 14 species are endemic and 154 threatened, respectively. Based on the distribution characteristics of mammals, the Yangtze River Basin were divided into 19 regions by deep rivers and high mountains. Except the headwater of the basin, species richness, G-F diversity index and the proportion of endemic species decreased gradually from the headwater to the estuary of the basin with a gradient of the elevation, and formed three value scales by Sichuan Basin and Yuanjiang River. Based on the species distribution in 19 regions (Jaccard similarity), cluster analysis was used to analyze the similarity of mammals. The 19 regions were clustered into four groups: (1) the headwater of basin, (2) Hengduanshan Mountain region, Yunnan Plateau, Sichuan Basin and QinlingDabashan Mountains, (3) Guizhou Plateau, Jiangnan hills, the plains in Poyang Lake and the delta of the Yangtze River basin, (4) Huaiyang mountains, Dongting Lake plain and Jianghan plain (or the Two-Lake plains), and the Lower reaches of the Yangtze River Basin. This grouping results responds to the environmental characteristics of the total basin and three large topographic platforms of the Chinese mainland.