Helicobacter pylori infection is the major etiological factor of chronic active gastritis and most peptic ulcer disease，and is closely associated with gastric cancers such as adenocarcinoma and MALT lymphoma. Since the Hp adhesin conservative region(AB) is outer membrane protein and porin type component, while these two kinds of protein are the excellent immunogen candidates of vaccination. The gene ab was amplified by PCR and inserted into the prokaryotie expression vector pET-22b（+）and expressed in the BL21（DE3）E.coli strain. DNA sequenced showed one open reading frame of 588 bp,which encoded polypeptides of 195 amino acids. SDS-PAGE and scan analysis show the AB molecular mass is 22.5 ku and recombinant protein amounted to 29% of the total bacterial protein. The AB purity amounted to 96% through affinity chromatography. Western blot analysis of AB confirmed it could be specially recognized by serum from rabbit immunized with AlpA.Acquire of AB established foundation for further studying the molecular adhesin, prevention and cure immunity mechanism of the adhesin.