The　balance　in　bacterial　community　is　very　important　for　the　maintenance　of　the　health　status　in　the　hosts.　During　the　occurrence　of　a　pervasive　skin　ulcer　disease　in　Sepia　pharaonis,　,　bacterial　isolate　H1　and　its　antagonist　bacterial　isolate　H2　were　simultaneously　isolated　from　the　healthy　cuttlefish,　but　only　bacterial　isolate　H1　was　isolated　from　the　diseased　cuttlefish.　In　the　present　study,　the　genetic　and　biochemical　analysis　showed　that　isolate　H1　was　identified　as　Vibrio　alginolyticus,　,　and　isolate　H2　was　identified　as　Pseudoalteromonas　piscicida,　,　respectively.　The　antibiotic　susceptibility　test　using　CLSI　M45-2015　method　showed　that　the　antibiotic　resistance　of　V.　alginolyticus　H1　and　P.　piscicida　H2　was　different,　and　V.　alginolyticus　H1　showed　strongly　resistance　to　ampicillin.　LD50　50　was　calculated　based　the　infection　using　immerse　infection　experiment.　The　result　showed　that　the　LD50　50　for　7　d　of　V.　alginolyticus　H1　was　1.58　x　106　6　CFU/mL,　while　the　no　death　was　observed　during　the　infection　of　P.　piscicida　H2.　Since　the　virulence　related　factors　were　significantly　influenced　by　host　immunity,　the　virulence　factors　of　pathogen　V.　alginolyticus　H1　was　assessed　under　the　stressors　of　H2O2　2　O　2　and　2,2　＇-dipyridyl.　＇-dipyridyl.　The　results　showed　that　the　pathogenicity　of　V.　alginolyticus　H1　was　associated　with　the　haemolytic　activity　and　bacterial　motility.　Different　components　of　the　P.　piscicida　H2　were　collected　and　were　tested　for　the　antagonistic　activity.　It　was　unexpected　that　no　antagonistic　substance　was　detected,　while　V.　alginolyticus　H1　showed　obvious　phobotaxis　to　P.　piscicida　H2.　It　could　be　concluded　that　V.　alginolyticus　H1　was　a　pathogen　of　S.　pharaonis,　,　and　P.　piscicida　H2　was　a　potential　antagonistic　bacteria　to　inhibit　V.　alginolyticus　H1　via　chemotaxis　instead　of　producing　antagonistic　substance.