Five bacteria strains were isolated from the skin ulcer and internal organ of the Acanthurus glaucopareius. The artificial infection test proved that the isolated strain was the pathogenic bacterium. Its morphological, physiological and biochemical characteristics were studied, and they completely matched Vibrio alginolyticus. The 16S rDNA gene was amplified by using the universal primers, and the PCR product was cloned and sequenced. A sequence of 1 392 base pair (bp) was obtained from the bacteria.The sequence was similar to the sequence of Vibrio alginolyticus(accession No.GQ455008), and the similarity was 99%. Vibrio alginolyticus was confirmed to be the pathogenic bacterium. The drug sensitivity test of bacteria strain revealed that the pathogen was sensitive to drugs such as furazolidone,norfloxacin and ciprofloxacin，and the pathogen was resistant to drugs such as methoxamine pyrimidine, ampicillin, amikacin and penicillin.