Objective　To investigate the species composition and spatial distribution of small mammals in the mountainous region of southern Pu’er, Yunnan province, China. Methods　During 2011 to 2012, a field survey was carried out at 19 villages and towns in four counties (districts) in southern Pu’er, i.e., Simao, Lancang, Menglian, and Jiangcheng. Small mammals were captured with small beast traps in an altitude range of 700-2000 m, covering six altitude gradient belts (Ⅰ-Ⅵ) and five major habitats (A-E). The richness of animal species, genera, and families was analyzed using the Shannon?Wiener diversity index. Results　A total of 787 individual small mammals were captured and classified into 21 species of 11 genera, which belonged to 5 families of 3 orders, i.e., Rodentia, Insectivora, and Scandentia. Of these, the predominant species were Rattus tanezumi (30.24%), R. brunneusculus sladeni (19.95%), and Crocidura dracula dracula (10.04%). Geologically, the richness of small mammal genera and species presented a gradually increasing trend from east to west. In different vertical zones, there were 11 species (5 genera, 3 families) of small mammals in belt Ⅰ (700 m-), 14 species (10 genera, 4 families) in belt Ⅱ (900 m-), 17 species (9 genera, 5 families) in belt Ⅲ (1100 m-), 7 species (4 genera, 4 families) in belt Ⅳ (1300 m-), 13 species (7 genera, 5 families) in belt Ⅴ (1500 m-), and 12 species (7 genera, 4 families) in belt Ⅵ ( 1700 m-). By comparison, the richness of small mammal species, genera, and families was higher in belts Ⅱ and Ⅲ (around 1000 m) than in the other belts. In the major habitats, there were 13 species (8 genera, 4 families) of small mammals in type A broadleaf forest, 19 species (11 genera, 5 families) in type B farmland in broadleaf forest, 17 species (10 genera, 4 families) in type C mountainous farming area, 5 species (4 genera, 4 families) in type D shrubbery, and 9 species (6 genera, 3 families) in type E forest tea-growing area. Among different habitats, the richness of animal genera and species was the highest in the farmland in broadleaf forest. Conclusion　The richness of small mammal genera and species presents a gradually increasing trend from east to west in the mountainous region of southern Pu’er, Yunnan. Among the 21 species of small mammals, R. tanezumi occurs as the predominant species with strong spatial distribution ability. There exist certain differences between different small mammal species in their selection and orientation of the environment as well as the ability of space resource utilization.