Abstract: Object To find the difference between the antimicrobial activity and the drug-resistance spectrum of E.Coli O157∶H7 strains. Method Antimicrobial susceptibility test was determined for 89 E.Coli O157∶H7 strains by using selected 19 common antibiotic agents in 1999. Results Over 90% of E.Coli O157∶H7 strains were susceptible to aminoglycosides、cephalosporins、fluoroqinolones、furazolidone、polymyxinB and chloramphenicol. We found that the drug-resistance rate of the stains from poultry was higher than that from sheep and cattle. The positive rate of the drug - resistance stains without toxicity gene was more than the strains with toxicity gene. Conclu-sion By this study,we suggested that the antibiotic resistance of E.coli O157:H7 strains was probably depended on its toxicity gene.