Abstract: A census to bird species diversity was conducted in fragmented rainforest patches at Xishuangbanna,Yunnan Province,China from October to November,1993,and from March to May,1994.The sample localities were Mane Holy Hill (3 ha) and Chengzi Holy Hill (4 ha) at Menglun,Mengla county,and Manyangguang Holy Hill (20 ha) at Xiaojie,Jinghong County.The control locality was a part of Xishuangbanna National Nature Reserve at Menglun (census area was about 100 ha).104 species,which belonged to 27 families (4 subfamilies),8 orders,were recorded in above localities.In the reserve,89 species were observed.At Manyangguang Holy Hill,30 species were found.Both at Mane and Chengzi Holy Hills 38 species were recorded.The Shannon index was highest at the reserve,while it was lowest at Manyangguang.At Mane the Shannon index was slightly higher than at Chengzi,but a t-test showed they were not significantly different.The change in trend of evenness was similar to that of Shannon index.11 species were common at all four localities.The species found at all three holy hills were also those 11 species.The number of species recorded at both the reserve and Chengzi were the highest (36 species),while the number of species recorded at both Manyangguang and Chengzi was the lowest (13 species).A dendrogram constructed by using the Jaccard index showed that similarity between Chengzi and the reserve was the highest (0.3956),while similarity between Mane and Manyangguang was the second highest (0.3878).This is probably because habitats around Mane and Manyangguang were similar to each other.Both sites were surrounded by farm land and rubber plantation.There was a large secondary forest at one side of Chengzi.This showed that the more similar the surrounding habitats,the more common the species at the two localities were.A dendrogram constructed by using the Sorenson quantitative index also showed that similarity of Mane to Manyangguang were the highest,Chengzi had a higher similarity to them than to the reserve.The reason for this was that the size of all three holy hills were small and the species number were low.However,Mane(3 ha) was more similar to Manyangguang (20 ha) than to Chengzi (4 ha).This showed the surrounding habitat also was one of factors affecting the Sorenson quantitative index,at least in small rainforest patches.A dendrogram constructed by using the Morisita-Horn index showed that there was highest similarity between Mane and reserve.Chengzi had a higher similarity to them.Manyangguang had the lowest similarity to all other localities.The change in trends of similarity was similar to that of their distance to larger primitive rainforest.Bird species number and Shannon index had the similar change trend as the plant species number and Shannon index.The 5 factors,pathch size,the distance to large primitive forest,plant community and diversity,human disturbance,and the habitats surrounding the patches,had influence on bird abundance and diversity in small rainforest patches.