[Objective] The aim of this study was to study the main serotypes and the biological characteristics of Avian Pathogenic Escherichia coli (APEC) isolated from Jiangsu and Anhui provinces. [Methods] The tested strains were isolated from sick poultry and identified by slide agglutination to determine serotypes. Virulence-associated genes were identified by PCR and the drug susceptibilities were detected according to Clinical and Laboratory Standards Institute (CLSI). Moreover, the biofilm-forming abilities were detected through improved crystal violet semi-quantitative method. [Results] In total 56 strains were isolated and identified. Slide agglutination results show that O78 was the main serotype accounted for 64.29% of the isolates. PCR amplification results of the virulence-associated genes showed that fimC, pfs, ompA and luxS were amplified from more than 90% of the tested strains. Drug sensitivity test results showed that 58.93% of the strains were resistant to more than 8 antibiotics. Biofilm formation assay showed that 16 isolates produced moderate or strong biofilm in vitro, in which 68.75% were resistant to more than 8 antibiotics. [Conclusion] O78 was the main serotype among the isolates. The genes of fimC, pfs, ompA and luxS were conserved in APEC. Multi-antibiotic resistance was very common and drug resistance seemed relative to biofilm-forming ability.