Abstract: Objective To establish a simple and reliable method for measurement of SEO serotype in Hantan virus.Methods Total NP gene and its type specific region gene were amplified by reverse transcription polymerase chain reaction(RTPCR).After TA clone,vector constr uction fo Cui-ss,Cui-155 baculovirus and transposition,recombinant baculovirus was obtained.By reinfection of Sf9 cell,expression was achieved.Results Expression product which cloning and expressing total NP coding region and type specific coding region(amino acid from 155 to 429)was in full agreement with VeroE6 cell infected by virus str ain in reaction band.Expression product could combine with its type specific McAb.Conclusion The method of clone and expression of the SEO virus antigen from NP and NP type specific region coding gene was established,and made simple and reliable measurement method of SEO serotype in Hantaan virus possible.