Vibrio harveyi cause mass mortalities of cultured marine fish. To address the ecology of V. harveyi in aquaculture, intensive monitoring is needed. We first optimized a quantitative real-time PCR method to determine V. harveyi abundance. The designed TaqMan probe and primers based on the 16S rRNA gene were specific at 68℃ of annealing and extension. Furthermore, the method using a chelating resin method was able to enumerate 1.7×10^2 CFU/ml in breeding seawater at an abalone farm. This method represents a good tool for monitoring the ecology of V. harveyi in marine environments within 5 h.