The aims of this study were to investigate the development,stability,cross-resistance and preservation of Aeromonas hydrophila resistance to tetracyclines and fluoroquinolones. A.hydrophila was grown at 28 ℃ for 72 h and used it to test for the development of resistance after 9 sequential subcultures in sub-inhibitory concentrations of two tetracyclines(doxycycline and tetracycline) and two fluoroquinolones (norfloxacin and levofloxacin).After 9 subcultures the minimal inhibitory concentrations (MIC) to tetracyclines were 8-32 times greater than the initial values，MIC values to fluoroquinolones were 125-7 997 times greater than the initial values,and drug-resistance were stable.The doxycycline-resistant isolate was resistant to tetracycline and fluoroquinolones,and the levofloxacin-resistant isolate was resistant to tetracyclines and norfloxacin.The drug-resistance stability test indicated that long-term storage of the bacteria at 4℃ could reduce their resistance to antimicrobials.