Abstract: Objective: To construct recombinant plasmid with fusion gene Tat_47-57-HBcAg,express fusion protein Tat_47-57-HBcAg in E.coli and identification the Tat_47-57-HBcAg by western blot analysis.Methods: To synthesize the sequence of Tat_47-57 and amplify HBcAg gene by PCR,splice the two sequences with splicing by overlap extension PCR,link fusion gene into pET28a,the sequences correct vector be transformed into E.coli Rosetta-gami^TM 2(DE3),then the transformed E.coli is induced by isopropyl β-D-1-Thiogalactopyranoside and the expression product is analyzed by SDS-PAGE,furthermore,identification the expression product by Western blot with HBcAg monoclonal antibody.Results: Fusion protein Tat_47-57-HBcAg is highly effective expressed in E.coli Rosetta-gami^TM 2(DE3).The solubility analysis of expression product indicated that the fusion protein are mostly expressed in supernatant and expression product could react with HBcAg monoclonal antibody by western blot analysis.Conclusions: The Tat_47-57-HBcAg fusion protein can be expressed in E.coli Rossetta-gami 2 correctly as soluble protein and be recognized by HBcAg monoclonal antibody.