Abstract: In order to clarify the adaptation mechanism of Leptocybe invasa to different Eucalyptus, traditional isolation and which combined with 16S rDNA identification were carried out to isolate and identify the bacteria in the L. invasa adults parasitized DH 201−2(E. grandis × E. tereticornis) and Eucalyptus exserta, then the influence of different hosts on culturable bacteria in L. invasa could be find out. The findings indicated that L. invasa parasitize DH 201−2 hold a higher index in the variety and diversity of culturable bacteria, compairing with which parasitized Eucalyptus exserta. The culturable bacteria isolated from L. invasa parasitized DH 201−2 could be divided into 4 phyla, 6 classes and 15 genera. The index of richness, dominance, diversity and evenness of the bacteria from 4 phyla were 0.90, 0.84, 2.03 and 0.72, respectively. Bacteria isolated from L. invasa parasitized Eucalyptus exserta could be divided into 4 phyla, 5 classes and 9 genera. The index of richness, dominance, diversity and evenness of the bacteria from 4 phyla were 0.59, 0.73, 1.60 and 0.67, respectively, which were lower than the former. Apart from the common Pantoea, L. invasa both parasitized DH 201−2 and Eucalyptus exserta also had another 2 genera of vivo dominant bacteria, that is, Staphylococcus and Curtobacterium. These results indicated that host plants could significantly affect the species, community structure and diversity of bacteria in L. invasa.