Abstract: OBJECTIVE To investigate the resistance mechanism of Escherichia coli to quinolones. METHODS The clinical isolates were derived from 348 isolates of E.coli isolated from our hospital from Jan. 2013 to Dec. 2016, and the repeated strains isolated from the same part of the same patient were excluded. The agar dilution method was used, and the MIC value of the isolate was calculated according to CLSI 2007. The resistant strains were screened out, and 7 kinds of common antimicrobial agents were added to determine the antimicrobial susceptibility of quinolones-resistant strains to other antimicrobial agents. The DNA of drug-resistant E. coli strains was extracted, the appropriate primers were added for amplification, and they were taken for comparison and analysis. RESULTS In the 348 isolates of E. coli, 87 strains were quinolones non-sensitive strains, accounting for 25.00%. The resistant rates of 87 strains of quinolones non-sensitive strains to gentamicin, amikacin, cefotaxime, cefepime, ceftriaxone, and ceftazidime were all more than 50%. The mutations of gryA resistance gene in E.coli were mainly occurred in low level MIC resistant strains. The drug resistance genes of parC and PMQR were mainly occurred in the resistant strains with MIC values of 4 ~ 8μg / ml and 16 ~ 64μg/ml. There were no significant differences in mutations between the two sites of S83L and D87N of gryA gene and S80I and A108V of gryC gene in the range of MIC value. CONCLUSION The non-sensitive E. coli of quinolone antibiotics are also resistant to many other antibiotics. The resistance gene of E. coli has some correlation with the distribution of MIC value of quinolone antibiotics.