Abstract: For obtaining the reombinant diagnostic antigen of Hantavirus,pBV220 -H1.3S was constructed which contained gene segment coding the Nucleocapsidpro tein (NP) o f hantan virus strain 76118.After this plasmid was transformed to and expressed in E.coli, It was found by SDS -PAGE that a new protein emerging in the baoteria cells with the Molecular Weight of about 48KD which is consistent with that of NP.Through purification of inclusion body, the recombinant NP (rNP)was used as coating antigen in Enzyme linked Immuno - sorbent Assay, detecting the specific IgG in 48 sera of suspect patients of Haemorr hagic Fever with Renal Syndrome.The result coincided with tha t by indirect immuno-fluorescent Assay by percentag e of 100, 92.88 and 93.75 for neg ative, positiv e and all samples respectively.The da ta indicated that this rNP was effective and valuable for use as diagno stic antigen.