Abstract: Pathological bacteriawere isolated from diseased flounder sufferd bacterial septicaemic infection in Qinhuangdao. Iden-tification of morphological, culturing, physiological and biochemical characteristics to 12 pure cultures and detection of themol%G+ C ratio of the DNA to representative strain, showed that the pathogenic bacteria belonged to a new species of Vibrio (pacini 1854) and were designated as Vibrio qinhuangdaora sp.nov. Simultaneously, we conducted examinations on thehomologyof serum, the results showed that the tested 12 strains have the same O-antigen and the sameK-antigen.In addition, the suscept-ibilities of isolates to 37 antimicrobial agents were detected, the results showed that all the strains were sensitive to cefazolin etal.,were resistant to penicillin G et al., and there isn. t obvious discrepancy of sensitivity and resistance between strains.