Objective To get recombinant antigen including the antigen epitope of gB protein for the detection of B virus. Methods The gene fragment of the antigen epitope sequences of gB protein was synthesized and directly cloned into the pET-22b vector. The positive recombinant vector was transformed into BL21 competent cells and induced with IPTG. Results The synthesis gene fragment was expressed successfully in the Prokaryotic cells on the soluble form. Conclusion Prokaryotic expression system can produce soluble B virus gB protein antigen and can be used as the detection of B virus antigen