Onion yellow dwarf virus（OYDV） is one of the major viruses that damage the quality and yield of shallot.In this study, OYDV was isolated from the tiller onion plantation in Nongan County, Jilin Province, and the OYDV cp gene was cloned by RT-PCR. The recombinant plasmid pET28-OYDV-cp was constructed and transformed into Escherichia coli strain Rosetta. Then cp was expressed and purified after induction and was identified as OYDV cp protein by Western-blot. The reaction analysis of OYDV cp protein with 9 monoclonal antibodies against Soybean mosaic virus showed that three monoclonal antibodies（2D3, 4F9, 4G12） could recognize specifically OYDV. In summary, OYDV cp was isolated from the tiller onion for the first time. The recombinant cp was obtained by prokaryotic expression, and three strains of monoclonal antibody capable of recognizing OYDV were identified, which provided antibody material for the detection of OYDV.