Pathogenic E. coli is the most common pathogen in humans and animals. As the symbiotic bacteria in the gastrointestinal tract, E. coli can become a reservoir of the drug resistance and resistance genes. Therefore, resistance level of E.coli can indirectly indicate the risk of resistance, which individual is exposed. This project aims (1) to investigate the resistance information of E. coli, which will be collected from main pig farms in Xinjiang, to three common antibiotics, quinolones, aminoglycosides, and β-lactams, by the microdilution method; (2) to detect the resistance genes of resistant strains to the three antibiotics; (3) to determine the genetic relationship of positive strains by PFGE; and (4) to study the molecular mechanisms by which resistance is transferred in E. coli by southern hybridization, analysis of plasmid transferability and incompatibility, mapping and analysis of genetic elements which mediate the transfer of resistance genes. This project may reveal the epidemic dissemination mechanisms of multi-class resistance genes and improve the understanding that the drugs we used for animals may promote the production of resistant drugs as well as resistant genes.