[Aim]  To explore the bacterial community structure of the Periplaneta americana and investigate how it acquires and carries pathogenic bacteria. Additionally, to determine the potential benefits of these bacterial communities to the host, to gain a greater understanding of how microorganisms promote the growth and development of P. americana. The findings of this study may offer valuable guidance for the artificial breeding of P. americana, and insight into reducing the risk of disease transmission. [Methods]  High throughput 16S rRNA amplicon sequencing was used to analyze the bacterial community diversity in surface and internal samples of wild and artificially reared P. americana. Additionally, PICRUSt2 was used to predict community functions based on the composition and abundance of 16S rRNA. [Results]  The abundance of the bacterial communities in the surface samples were lower compared to the internal samples. Moreover, the surface samples from the wild populations had significantly higher α and β diversity compared to the artificially reared populations (P<0.05). However, there was no significant difference in the internal samples between the wild and artificially reared populations (P>0.05). At the phylum level, both the surface and internal samples of P. americana were primarily dominated by Bacteroidetes (average abundance: 22.91% on the surface and 64.07% internally), Proteobacteria (48.49% on the surface and 12.83% internally), and Firmicutes (20.26% on the surface and 15.79% internally). Significant differential features between different treatments were identified through linear discriminant analysis effect size (LEfSe). Notably, in both the wild population and cutaneous samples, we observed a significant presence of pathogenic bacteria from the genus Serratia, Acinetobacter, and Enterococcus. Functional predictions using PICRUSt2 revealed that the bacterial community in the internal samples of P. americana has a higher proportion of functional categories related to environmental adaptation, amino acid metabolism, energy metabolism, carbohydrate biosynthesis and metabolism, nucleotide metabolism, replication, and repair. Additionally, the proportions of these functional categories associated with the microbial community were significantly higher in the internal samples compared to the surface samples (P<0.05). [Conclusion]  The internal bacterial community of P. americana is relatively conservative and resistant to change, and plays a crucial role in nutrient metabolism, environmental adaptation, and immune enhancement. The pathogenic bacteria in P. americana are primarily acquired from the environment and mainly adhere to the surface for transmission. Therefore, a diversified diet should be offered to artificially farmed P. americana to prevent disrupting its gut microbiota structure, which could impact its normal growth and development. Additionally, it is crucial to maintain hygienic conditions in P. americana breeding facilities to reduce the risks of proliferation and transmission of pathogenic bacteria.