Abstract: The objective of this study was to utilize pCold-SUMO expression vector to efficiently express capsid（Cap）protein gene without nuclear localization signal (NLS) of porcine circovirus 2 (PCV2).Cap gene without NLS was subcloned into the pCold-SUMO expression vetor, which named as pCold-SUMO-dCap, and the recombinant plasmid was transformed into Arctic-Express competent cells.It was induced by IPTG at 15 ℃ and efficiently produced active fusion protein of SUMO-dCap. SDS-PAGE analysis of the recombinant protein demonstrated that soluble SUMO-dCap in the supernatant was expressed at approximately 50% of total recombinant fusion proteins.Then,the soluble SUMO-dCap was purified by Ni-NTA resin purification kits, whereas the SUMO tag was removed by SUMO protease.In addition,the purification effect and specificity of recombinant fusion protein and capsid protein without NLS were detected by Western-blot assay.The results showed that both of them had been well purified and possessed good reactionogenicity.