Abstract: Xishuangbanna is one of three areas where tropical rain forest can be found in China.Ant communities of montane rain forest in nature reserve area and 3 fragments in Xishuangbanna were compared through a sampling investigating method.Our aim was to reveal the distance influence upon the ant communities.Seventy-four ant species belonging to 6 subfamilies and 35 genera were collected in 4 types of sample plot.Fragments with different distance from nature reserve area had their own endemic species separately (10-11 species),but the number was all less than that of nature reserve area (15 species).With the distance from nature reserve area increasing,the common species of fragment and nature reserve area decreased (from 5,3,to 2 species),but percentage of the most important dominant species Pseudolasius silvestrii Wheeler increased (from 26.36% to 69.12%).The number of species in nature reserve area (15 species) was distinctly larger than in fragments (26-29 species).Individual density in nature reserve area (547.8/m2) was higher than in fragments,and the density of fragments increased (from 172.4/m2,209.4/m2,to 364.6/m2) with the distance from nature reserve area increasing.Among the 4 sample plot types,fragment 1,which was closest to nature reserve area,rather than nature reserve area,had the maximum of species diversity index and evenness index (2.767 and 0.830 respectively).With the distance from nature reserve area increasing,species diversity indices and evenness indices of the 3 fragments decreased,but predominant indices increased.Similarity coefficient between nature reserve area and 3 fragments decreased (from 0.29,0.24,to 0.15) with distance from nature reserve area increasing.The results show that distance has great influence upon ant communities in fragments of montane rain forest,and fragmentation is harmful for biodiversity protection.