Abstract: 【Objective】The purpose of the study was to analyze the composition and diversity of gut bacterial communities in different developmental stages of the natural enemy insect Eocanthecona furcellata(Wolff), and to predict their functions, in order to provide a theoretical basis for a deeper understanding of the influence of gut bacteria on the growth, development and nutrient acquisition patterns of E. furcellata, as well as for the development of a novel biocontrol strategies for the pests. 【Method】The gut bacterial genomic DNA was extracted from the first instar nymphs, second instar nymphs, fifth instar nymphs, 7-day-old female and male adults of E. furcellata, respectively. The full-length of 16S rRNA sequence of E. furcellata gut bacteria was sequenced using the single-molecule real-time sequencing technique. The number of operational taxonomic unit(OTU) was counted, the composition and diversity of gut bacterial communities were analyzed, and the functions of gut bacteria were predicted by PICRUSt. 【Result】A total of 202401 effective sequences were obtained from 15 gut samples of E. furcellata, and clustered into 222 OTUs, of which 5 OTUs were shared by them. A total of 19 phyla, 32 classes, 62 orders, 103 families, 154 genera and 188 species bacteria were annotated. The dominant phylum, class, order, family, genus and species of the bacteria were Proteobacteria(72.22%), Gammaproteobacteria(72.21%), Enterobacterales(72.11%), Enterobacteriaceae(49.39%), Cedecea(49.24%), and C. neteri(49.24%), respectively. The results of the diversity and variance analysis revealed significant differences in the composition of the gut bacterial flora in different developmental stages of E. furcellata(P<0.05, the same below). The linear discriminant analysis results showed that significantly dominant flora existed in the guts of first instar nymphs, second instar nymphs and 7-day-old female and male adults, while no significantly dominant flora existed in the gut of fifth instar nymphs(P>0.05), and the dominant flora in the gut of different developmental stages varied at the level of 3 taxonomic categories, namely, family, genus and species. KEGG metabolic pathway analysis revealed that the functions of the gut flora of E. furcellata were similar in different developmental stages, mainly involving metabolism(74.17%-75.59%) and environmental information processing(10.53%-11.03%). The secondary metabolic pathways were mainly global and overview mapping, sugar metabolism, and amino acid metabolism, etc. 【Conclusion】Significant differences in the composition and diversity of gut bacterial community are observed in different developmental stages of E. furcellata, and the distribution of dominant bacteria shows dynamic changes.