Abstract: 【Objective】To study the diversity of culturable bacteria in the intestines of critical instar larvae of Dendrolimu kikuchii, and to explore the resources and diversity of intestinal bacteria, so as to lay a foundation for further research on the function of insect intestinal microorganisms and population management of D.kikuchii.【Method】Traditional methods of microorganism isolation, pure culture and identification were used to isolate and purify the intestinal bacteria from the 1^st, 4^th, and 7^th instar larvae collected from the forest area of Caopu Town, Anning City, Yunnan Province.The 16S rDNA sequence homology analysis of the isolated bacteria was conducted to preliminarily determine their taxonomic status and conduct diversity analysis.【Result】A total of 291 strains of bacteria were isolated from the intestines of D.kikuchii larvae, belonging to 31 species of 15 genera.Among them, 98 strains of the intestines of the 1^st instar larvae belonged to 13 species of 9 genera, 102 strains of the 4^th instar larvae belonged to 12 species of 6 genera, and 91 strains of the 7^th instar larvae belonged to 9 species of 6 genera.Among the 31 bacterial species, Bacillus was the most, with 9 species, accounting for 29.03%, followed by Enterobacter and Staphylococcus with each 4 species, accounting for 12.90% of the total species respectively.Among the thirteen 1^st instar larvae, the relative isolation rates of Staphylococcus, Enterobacteria and Bacillus were 27.54%, 21.43% and 21.43%, respectively, which were higher than the average isolation rates of other bacteria(5.31%).Among the twelve 4^th instar larvae, the relative isolation rate of Bacillus was 72.53%, higher than the average isolation rate of other genera(5.49%).Among the nine 7^th instar larvae, the relative isolation rates of Klebsiella and Enterobacteria were 43.96% and 18.68%, respectively, which were higher than the average isolation rates of other bacteria(9.34%).The dominant index, richness index and Shannon-Weiner index of intestinal bacteria of the 1^st instar larvae were the highest, which were 0.9032, 2.6172 and 2.4310, respectively.The evenness index of intestinal bacteria of the 7^th instar larvae was the highest, which was 0.9634.【Conclusion】The composition and structure of culturable bacterial communities of the 1^st, 4^th and 7^th instar larvae in the intestines of D.kikuchii are rich, and there are abundant bacterial resources.