Objective Bacteria carried inside and outside the body of Periplaneta americana were studied, which were collected from different environment, and the relationship between the bacteria and the living environment of P. americana were analyzed. Methods Periplaneta americana were collected from the port, hospital and residential areas. 16S rRNA V3-V4 was selected as the target gene 4-5 individuals were collected from each area as replicates. Bacteria carried inside and outside the body of P. americana were studied by cloning method. Results Totally 139 genera, 202 species of bacteria from P. americana were obtained, including 22 genera, 44 species pathogenic bacteria, only 11 out of the 202 detected species were the same. In total, 55 genera, 65 species were obtained from the port, of which 16 genera, 21 species were pathogenic, and only 2 same species were detected among the different individual P. americana. Seventy three genera, 86 species were identified from the residential area, of which 13 genera, 19 species were pathogenic, none of the same bacteria were detected among the different individuals. Sixty eight genera, 101 species were obtained from the hospital area, of which 15 genera, 25 species were pathogenic, only 2 same species were detected among the different individuals. Conclusion Few same species of the bacteria were detected from the different individual P. americana from the same area, or the same species from different areas, so it was quite difficult to conclude the relationship between the bacteria carried by cockroach to its living environment, but more pathogenic bacteria and conditional pathogenic bacteria were detected from the P. americana from the port and hospital areas, so the surveillance of the cockroach should be strengthened in these areas.