Abstract: In order to obtain the chimeric protein and bispecific antibody of the fusion protein（F） of Newcastle disease virus（NDV） type Ⅶ and outer membrane gene A（OmpA） of avian pathogenic Escherichia coli（APEC） type O18, firstly, the F gene of Newcastle disease virus type Ⅶ and OmpA gene fragment of APEC type O18 were obtained by gene synthesis technique. Homologous recombination technique was used to insert F gene into OmpA gene, and then the recombinant gene fragment was inserted into the prokaryotic expression vector pGEX-4T-1 to construct chimeric expression plasmid. The insertion gene sequence in the recombinant plasmid was sequenced and identified. The chimeric expression plasmid with correct sequence was transformed into BL21（Rosetta） Escherichia coli（E. coli）, and inducing chimeric protein expression using IPTG. The expression of chimeric proteins was detected by SDS-PAGE and Western-blot. After purification of chimeric protein, rabbits were immunized to obtain antiserum, and antiserum was purified by antigen affinity purification chromatography column to obtain polyclonal antibodies. Enzyme linked immunosorbent assay（ELISA） was used to determine the antibody titer. The results showed that Fo, OmpA1 and OmpA2 gene fragments were synthesized successfully, and the recombinant plasmid pGEX-O1-Fo-O2 was constructed and expressed; the purified chimeric protein O1FoO2 existed in the form of inclusion body in Escherichia coli; the titer of the prepared polyclonal antibody against O1FoO2 was about 1.1×10~6; the titer against GST was about 4.1×10~4. The results indicated that the quality of chimeric protein and bispecific antibody was good.