Objective To construct an Escherichia coli outer membrane protein-A (OmpA) gene-deleted strain by Red homologous recombination, and laid the foundation for subsequent research. Methods Polymerase chain reaction (PCR) primers were designed according to the known OmpA gene sequence, and plasmid pKD3 for PCR amplification and integration; the fragment was transformed into Escherichia coli by λ-Red system in plasmid pKD46. After PCR checking and sequencing confirmation OmpA protein knocked out was observed by Western-blotting. Results The knock out gene product was correspond to a expected molecular weight. The western-blotting show that OmpA protein was knocked out. The difference in growth curve between the wild type and Escherichia coli △ OmpA gene-deleted strain was not significant. Conclusion OmpA gene deletion had no significant effect on the growth of Escherichia coli, which provides a foundation for further research on live vector vaccine.