Abstract:The objective is to study the expression of porcine circovirus capsid protein in the Bacillus subtilis. Based on 3 different plasmids,different types of recombinant vectors for porcine circovirus capsid protein gene(PCV2-ORF2)were constructed,and they were transformed into strain 168 and WB800 of B. subtilis. The expression of the target protein was detected by SDS-PAGE and Western blot,and the mRNA expression of the target gene in B. subtilis was detected through RT-qPCR. The original ORF2 was difficult to be translated in B. subtilis expression system. After the codon optimization,truncated ORF2 gene was successfully expressed as target protein in intracellular expression system of B. subtilis. Thus,the optimization of the codons promoted the expression of the target gene.