【Objective】To express the capsid protein (Cap) of porcine circovirus type 2 (PCV2) in insect cells and analyze the immunogenicity of recombinant protein.【Method】The established recombinant bacmid containing fused ORF2 gene (Bacmid-ORF2) was transfected into insect cells for protein expression test, and then the purified *Cap and pcDNA3.1-ORF2 plasmid were immunized mice respectively to compare their immunological effects.【Result】The Cap structural protein encoded by PCV2-ORF2 gene was correctly expressed in insect cells, and the relative molecular mass was about 32 000. *Cap could be recognized by PCV2 positive serum and had good antigenicity. The immue effect of *Cap group was better than that of pcDNA3.1-ORF2 group in both cellular immunity and humoral immunity levels.【Conclusion】The recombinant protein *Cap can replace the whole virus and may have potential application values of PCV2 vaccinum. These results lay the foundation for the study of molecular diagnosis, subunit vaccine development and molecular biology research of PCV2.