Many unrelated bacteria in phylogenetic relationship with TTX producing ability were isolated from various animals and environment, reminding us that horizontal gene transfer (HGT) might exist among various TTX producing bacteria, but the exact mechanism is unclear. The objective of this study is to investigate whether HGT related genes exist in the plasmid pNe-1 isolated from tetrodotoxin producing Aeromonas sp. The tra, rum and vird₄ genes were amplified by PCR. The 906 bp length tra fragment, 681 bp length rum fragment and 1 319 bp length vird₄ fragment had significant homology to some transposase, relaxase and vird₄ in sequence and contained conserved domains of these putative proteins respectively. The results indicate that the tetrodotoxin producing Aeromonas sp. has the ability to transfer genes by conjugation and transposition, and also has the ability to transfer TTX to the hosts. The result of research in this study is believed to be significant for the further understanding of the relationship among tetrodotoxin producing bacteria and the relationship between tetrodotoxin producing bacteria and the puffer fish.