To explore the diversity of bacterial community in Cobolidia fuscipes (Meigen), the V3~V4 regions of bacterial 16S rDNA in this insect species at different development stages were sequenced using Illumina MiSeq high-throughput sequencing platform. A total of 548 058 reads and 870 operational taxonomic units (OTUs) were obtained and annotated into 24 phyla, 51 classes, 92 orders, 175 families and 346 genera. The Chao, Ace and Shannon indices were 485.00~885.03, 485.09~877.55 and 2.90~4.31, respectively. The domi-nant bacterial phyla were Proteobacteria and Actinobacteria, dominant orders were Rhizobiales and Actino-mycetales, and dominant genera were unclassified Xanthobacteraceae, Pseudomonas and Leucobacter. However, the dominant genus in each sample was different. Pseudomonas occupied the highest proportion in eggs, unclas-sified Xanthobacteraceae had the highest relative abundance in the 1st to 3rd instar larvae and adults, Cory-nebacterium had the highest relative abundance in the 4th instar larvae, and Providencia had the highest rela-tive abundance in pupae. Principle component analysis (PCA) demonstrated that the composition of bacterial community in C. fuscipes (Meigen) was different at different development stages. This study provides a theoreti-cal basis for exploitation of microbial resources in C. fuscipes (Meigen) and also for biocontrol of the pest species.