Abstract: In order to improve the soluble expression of Porcine circovirus type 3（PCV-3） Cap recombinant protein, in the test, PCR was used to amplify PCV-3 Cap gene, which was inserted into the prokaryotic expression vector pET-32a（+） to construct the recombinant prokaryotic expression vector pET-32a（+）-Cap; and then the recombinant prokaryotic expression vector was transformed into Escherichia coli Rosetta（DE3） competent cells; the induced expression of the recombinant protein was analyzed by different concentrations of IPTG and temperatures. The effects of different concentrations of IPTG and temperature were analyzed, and the recombinant protein was identified by Western-blot. The results showed that PCR amplified a Cap gene fragment with a size of 645 bp, which was consistent with the expected results; the constructed recombinant prokaryotic expression vector pET32a（+）-Cap could be expressed in Escherichia coli Rosetta（DE3） competent cells, and the molecular weight of the recombinant protein was about 43.1 ku. Different concentrations of IPTG induced the expression of soluble proteins in different amounts, and the soluble expression of recombinant proteins was higher at the final concentration of 0.1 mmol/L IPTG. The recombinant protein was mainly expressed in the precipitate when induced at 37 ℃, and in the supernatant when induced at 20 ℃; the expressed recombinant protein was able to bind specifically to the antibody with His tag. The results indicated that the recombinant protein was successfully constructed, and more soluble proteins were obtained by low temperature induction.