A pathogenic Vibrio harveyi strain LY-1 was originally isolated from diseased Lateolabrax japonicus cultured in Ningbo, Zhejiang Province.873 bp-length fragment of ToxR gene cloned from the DNA of V.harveyi strain LY-1 was sequenced and showed that it shared high identity of 99% to those of V.harveyi in GenBank, and had lower similarities to those of V.parahaemolyticus, V.anguilarum, V.vulnificus, V.fisheri, V.alginolyticus, V.hollisae and V.mimicus, with only 27.62%~72.49% identity.A set of loop-mediated isothermal amplification (LAMP) primers were designed and synthesized based on the conservative sections of V.harveyi ToxR gene, and the LAMP for detection of V.harveyi was developed after optimizing the factors.LAMP required only a incubation at 65 ℃ for 45 min, and its detection limit for V.harveyi DNA was 1 fg, which was found to be more sensitive than the commonly used PCR method.To date, this is first report that LAMP method is used to detect V.harveyi rapidly.