Avian community diversity of the forest-steppe ecotone in southeast edge of Innermongolia tableland was studied in summer seasons from 2004 to 2006. A total of 73 species was recorded, which belonged to 56 genuses, 28 families and 13 orders. The avifanua had obvious character of the Palaeartic realm. The number of species and density of avian community among different years were not significantly different. The α diversity changed obviously with the variation of environment grades of forest-steppe ecotone. The number of species, densities, Shannon-Wiener indexes and Pielou indexes were different significantly between vegetation zones, but not for the diversity of family and genus. The character and change trend of all diversity indexes were as follows, forest zone＜forest-meadow region of ecotone＞meadow-steppe region of ecotone＞steppe zone（the index of DG-F was meadow-steppe region of ecotone＞forest zone）. The avian species diversity increased significantly in the forest-meadow region of ecotone, and the number of species and densities were maximum in this region, which showed obviously the edge effect of the ecotone. The avian community changed significantly in the meadow-steppe region of ecotone,in which species diversity decreased decreased significantly. The β diversity changed significantly along the different vegetation zones. The β diversity and specie replacement rate of were maximum in the forest zone-forest-meadow region and the meadow-steppe region-steppe zone, which had the biggest environment difference. There was a close relationship between the specie replacement rate and the environment grades. The composition and density of dominant species changed obviously in different vegetation zones. The number of bird species, density, species diversity had significant positive relationship with the forest patch number. In the large-scale space, the forest patch number is the most important factor to affect the bird community diversity.