Abstract: Three pathogenic bacteria were isolated from diseased Quasipaa spinosa, which were used to microbial regression experimental infection by oral, intramuscular injection, damaged skin immersion and no damaged skinimmersion. Results showed that in addition to the oral way, various other infection ways could cause disease and death of Quasipaa spinosa. Moreover, the bacteria had strong pathogenicity to Quasipaa spinosa. The isolated strain was identified as Aeromonas hydrophila by its morphological, biochemical properties and 16S rDNA sequence analysis. At the same time, the susceptibility of isolated strains to antibiotics was studied by zone of inhibition testing. Results showed: it was sensitive to chloramphenicol, pipemidic acid, cefoperazone, streptomycin, tetracycline, norfloxacin and gentamicin. However, it was not sensitive to penicillin, neomycin, clindamycin, cephalothin and erythromycin.