Stable higher level FQN-resistant strains of porcine E. coli were obtained by serial passages on agar containing subinhibitory concentration of CIP from four sensitive strains WJPE3-2, MYPE1-4, MSPE6, WJPE2-1. The results showed that different times of MIC values of CIP were promoted by induce test were between 4-512. Furthermore, the MIC values of Enrofloxacin, Norfloxacin and Oxfloxacin of each induced strain were also enhanced to different times.