Abstract: The diversity and species component of small mammal communities were measured with trap-day method in Alashan region of Inner Mongolia from August to September 1998 and 1999, and in October 2002. The 54 sites were selected in different habitats. The area of the site was 10 hectare in which 400-500 traps were arranged. A total of 866 individuals were captured with 22 606 trap-days during investigation period, and 20 species of small mammals were recorded in the study sites. The results of analysis on diversity of small mammal communities showed that Shannon-Wiener diversity index was 1.186 – 1.589; Pielou evenness index was 0.630 9-0.861 8; Simpson dominance index was 0.234 9 – 0.415 7; Margalef richness index was 0.931 8 -2.020. Based on similarity indices of the communities , the 8 communities could be clustered together at the level of 0.093 5 with systematic clustering , which could be divided into 4 types as follows: Drought2enduring type including community Ⅴand Ⅶ; Arid type including community Ⅰ, Ⅱ, and Ⅲ; Ecotone type that was from farmland to forest including community Ⅵ and Ⅷ; and Forest type including community Ⅳ. The diversity and species component of small mammal communities were determined by the difference of habitats and affected by human activities.

Key words: Small mammal, Community, Diversity, Habitat, Alashan region