According to published nucleotide sequence, ORF4 gene of Barley yellow dwarf virus GPV (BYDV-GPV) was synthesized by reverse transcription-polymerase chain reaction (RT-PCR) and inserted into expression vector pET-5a for overexpression in prokaryotic cells. The result of SDS-PAGE showed that specific expression of a 17 kDa protein was achieved after IPTG induction. The expressed protein was purified from SDS-PAGE gel and the antiserum against BYDV-GPV 17 kDa protein was raised in rabbit. The antiserum could be used for specific detection of the 17 kDa protein in oats infected by BYDV-GPV.