A fragment of hepatitis E virus open reading frame-2(ORF2), located from amino acid residues 394 to 604, was expressed in E. coli. The recombinant protein NE2 was found to form homodimer mostly in SDS-PAGE, which can be dissociated to monomers when treated with urea, and it was recognized more strongly in its dimeric form than the monomer by HEV reactive human serum in Western blotting. Besides, many aggregated form of NE2 from dimer to at least hexamer can be seen in MALDI-TOF-MS. And when the hydrated dynamic semidiameter of NE2 moleculars in PBS was measured as about 4 nm by Dynamic Light Scattering (DLS), being equal to tetramer, but with high polydispersity, which suggested that the NE2 moleculars were existed in PBS in many different sizes. These results suggested that the recombinant NE2 can aggregate into several oligomer forms, the association in the dimer is most strong, and dimers can assemble further to form some super-structure.