Abstract: An investigation of classⅠintegron and its gene cassette epidemiology in 192 Escherichia coli strains isolated from a swine farm was carried out by the methods of PCR, sequence, and restriction enzyme analysis. The result showed that one-hundred and five strains (54.7%) of E. coli harbored six types of classⅠintegron in the form of eight combinations. All of E. coli strains from the pigs, the raisers, and the surroundings had similar prevalence of classⅠintegron, but the strains with the same resistant patterns did not always carry the same type of classⅠintegron. Each type of classⅠintegron integrated different kinds and numbers of gene cassette. Among all the detected classⅠintegrons, one-hundred percent carried aminoglycoside adenyltransferase (aadA), seventy-seven percent carried dihydrofolate reductase (dhfr), whereas only a small percentage carried one or two of the beta-lactamase (bla), streptothricin acetyl-transferase (sat), and erythromycin esterase (ereA) genes. All E. coli strains carried classⅠintegrons were multi-resistant, especially resistant to compound sulfamethoxazole (100%), streptomycin (90%), and spectinomycin (75%). High prevalence of classⅠintegrons carrying dhfr and aadA genes had occurred in E. coli strains because sulfonamides and aminoglycosides were used extensively, especially used as antibacterial growth promoter in this swine farm.