Seventeen E. coli strains of clinical avian E. coli were used to detect irp2, irp3, irp4 and irp5 located in HPI and their biofilm formation ability among E. coli strains. Firstly, 7 strains of Avian pathogenic E. coli were detected using irp2 PCR amplification, ERIC-PCR genotyping of the strains was conducted, and the strains were divided into two types; secondly, 17 strains were detected and the results showed that the positive percentages of irp2, irp3, irp4 and irp5 were 41.2%, 64.7%, 29.4% and 35.3%, respectively; finally, the biofilm formation ability of the isolated strains of E. coli were determined and the result showed that the positive strains carrying irp2 have a strong ability of biofilm formation. The results suggested that Avian pathogenic E. coli carrying irp2 have some correlations with biofilm formation.