Abstract: Aeromonas hydrophila exists in the water body, which can cause many kinds of diseases and huge loss of aquaculture animals to the aquaculture production. The pathogenicity and virulence characteristics of the isolated strain which caused mass mortalities of reared Mandarin fish were studied. The rapid detection methods of A. hydrophila were established by the loop-mediated isothermal amplification (LAMP) using aerA gene as molecular marker. The results showed that the LD₅₀ of A. hydrophila was 1.6×10⁶ CFU/mL, and 14 virulence genes were detected from the isolated strain, which can be biology markers in detecting of pathogenic A. hydrophila. The assay of LAMP for detecting A. hydrophila was established using aerA gene as molecular marker. Positive reactions were detected by the stair-step amplified bands, and the green amplified products were observed directly by naked-eye in the reaction tube by addition of SYBR Green I. No any amplified bands and orange color were detected in control group. The results showed that LAMP detection method of A. hydrophila had good specificity. The results of sensitivity of LAMP showed that the primers could detect A. hydrophila at the level of 4.6×10¹ CFU/mL. The artificially infected 10 species of freshwater fishes and shrimps revealed positive amplified results using LAMP detection method, and no-infected 10 samples revealed negative amplified results. The results showed that the LAMP detection method has preferable application, and could be used in rapid diagnose of aquatic animal diseases caused by A. hydrophila.