Abstract: We collected root samples of Acacia crassicarpa, Acacia cincinnata, Acacia melanoxylon, Acacia mearnsil, and Acacia mangium. And through 16S rRNA high-throughput sequencing and statistical analysis, the diversity of endophytic bacterial communities in the roots of 5 Acacia species was compared. At the Class level, the dominant endophytic bacteria in the roots of A. crassicarpa, A. cincinnata, A. melanoxylon and A. mearnsil are Alphaproteobacteria, while Gammaproteobacteria dominates the endophytic bacteria in the roots of A. mangium. At the Order level, the dominant endophytic bacteria in the roots of A. crassicarpa, A. cincinnata, A. mearnsil and A. melanoxylon are Rhizobiales, while Rhizobiales, Enterobacteriales and Unidentified_Gammaproteobacteria dominate the root endophytic bacteria of A. mangium. At the Family level, the dominant endophytic bacteria in the roots of A. crassicarpa, A. cincinnata, A. mearnsil, and A. melanoxylon are Xanthobacteraceae, while Enterobacteriaceae dominates the root endophytic bacteria of A. mangium. The endophytic bacterial communities in the roots of different Acacia species are quite different at the level of Class, Order and Family. Compared with the dominant bacterial communities of the other 4 Acacia species, A. mangium showed specificity.