is an important pathogenic bacterium of most marine aquaculture animals that has caused significant losses within the aquaculture industry. The pathogenicity of is influenced by quorum sensing, meaning that population density plays a role in determining the outcome of an infection. Thus, there is a need to develop a method to detect the density of V. harveyi species-specificP2 gene to establish a SYBR Green I real-time fluorescence quantitative PCR detection method. A 151 bp gene fragment was amplified from the chromosomal DNA of from different sources. The primers did not cross react with nine other bacteria species using conventional PCR, suggesting the primer pair has good intra-species specificity and inter-species commonality. A recombinant plasmid containing the was constructed and used to construct the standard curve. The standard curve for the +37.48. The correlation coefficient was 0.998 and the amplification efficiency was 1.00, indicating that there was a good linear relationship between initial templates and values. The melting curve had only one specific peak at an annealing temperature of 60. The detection limit of the assay was seven copies per reaction, which is 10 000 times more sensitive than that of conventional polymerase chain reaction (PCR). The results of intra- and inter-assay variability tests demonstrated that the method was highly reproducible. Our results suggest that this SYBR Green I real-time PCR assay may be used for the rapid and accurate detection of from infected aquaculture species. This will allow early diagnosis of infection and improve the efficacy of disease prevention and surveillance programs.