[Objective] The core type of Escherichia coli lipopolysaccharide (LPS) is divided into 5 types, R1, R2, R3, R4 and K12, based on their different chemical structure. The aim of the present study was to study the distribution of LPS core type in avian pathogenic E. coli, and its correlation with virulence genes. [Methods] LPS core type and 17 virulence genes were detected in 76 strains of APEC by PCR. The correlation of LPS core type and virulence was analyzed. [Results] The core types of R1, R3, R4 and R2 were 68.4%, 15.8%, 11.8% and 3.9%, respectively. The virulence genes yijp, mat, fimC, ibeB and ompA were conserved in APEC strains. The R1 core type was significantly positive correlated with neuC, cva/cvi and irp2 (P<0.05), the R4 core type was positive correlated with aatA, whereas the R3 core type was negative correlated with iroN and irp2 (P<0.05). [Conclusion] R1 core type is more prevalent than other LPS core types and associated with high pathogenicity.