Abstract: We transformed the recombinant expression plasmid vector pRSET A-MCP of major capsid protein gene (MCP) of red-spotted grouper (Epinephelus akaara) nervous necrosis virus (RGNNV) into Estherichia coli BL21(DE3) and induced the bacterial cultures with IPTG．SDS-PAGE analysis shows that the recombinant protein with the molecular weight of 44.5 kD is presented in the form of inclusion body. The recombinant protein is purified by affinity chromatography on Ni-NTA-Agarose column with 90% purity and then is used to immunize the New Zealand rabbit. ELISA result demonstrates that the titer of antiserum is over 1:12 800. Moreover, the Western-blot result reveals that the antiserum has a strong reaction with the recombinant protein expressed from E.coli BL21, and the prokaryotic expression of recombinant protein is proved to have good immunogenicity.